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1.
J Colloid Interface Sci ; 462: 56-63, 2016 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-26433478

RESUMO

Stimuli-responsive protein surfactants promise alternative foaming materials that can be made from renewable sources. However, the cost of protein surfactants is still higher than their chemical counterparts. In order to reduce the required amount of protein surfactant for foaming, we investigated the foaming and adsorption properties of the protein surfactant, DAMP4, with addition of low concentrations of the chemical surfactant sodium dodecylsulfate (SDS). The results show that the small addition of SDS can enhance foaming functions of DAMP4 at a lowered protein concentration. Dynamic surface tension measurements suggest that there is a synergy between DAMP4 and SDS which enhances adsorption kinetics of DAMP4 at the initial stage of adsorption (first 60s), which in turn stabilizes protein foams. Further interfacial properties were revealed by X-ray reflectometry measurements, showing that there is a re-arrangement of adsorbed protein-surfactant layer over a long period of 1h. Importantly, the foaming switchability of DAMP4 by metal ions is not affected by the presence of SDS, and foams can be switched off by the addition of zinc ions at permissive pH. This work provides fundamental knowledge to guide formulation using a mixture of protein and chemical surfactants towards a high performance of foaming at a low cost.


Assuntos
Proteínas/química , Dodecilsulfato de Sódio/química , Tensoativos/química , Adsorção , Cinética , Tamanho da Partícula , Estabilidade Proteica , Propriedades de Superfície
2.
Soft Matter ; 11(21): 4218-25, 2015 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-25892050

RESUMO

Shape memory hydrogels offer the ability to recover their permanent shape from temporarily trapped shapes without application of external forces. Here, we report a novel dual-responsive shape memory hydrogel with characteristic thermoplasticity. The water-insoluble hydrogel is prepared by simple ternary copolymerization of acrylamide (AM) and acrylic acid (AA) with low amounts of a cationic surfmer, in the absence of organic crosslinkers. Through either ionic/complex binding of carboxyl groups via trivalent cations or salt-dependent hydrophobic association, the hydrogel can memorize a temporary shape successfully, which recovers its permanent form in the presence of a reducing agent or deionized water. Besides, the unique thermoplasticity of the hydrophobic polyampholyte hydrogel allows the change of its permanent shape upon heating and the fixation after cooling, which is in strong contrast to the conventional chemically cross-linked shape memory hydrogels. This fascinating feature undoubtedly enriches the shape memory hydrogel systems. Thus, we believe that the facile strategy could provide new opportunities with regard to the design and practical application of stimulus-responsive hydrogel systems.


Assuntos
Hidrogéis/química , Acrilamida/química , Acrilatos/química , Compostos Férricos/química , Hidrogéis/síntese química , Interações Hidrofóbicas e Hidrofílicas , Polimerização , Reologia , Cloreto de Sódio/química
3.
Macromol Rapid Commun ; 36(9): 845-51, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25765249

RESUMO

A novel thermally sensitive shape memory (SM) hydrogel is prepared by block copoly-merization of a cationic surfactant monomer, dimethylhexadecyl[2-(dimethylamino)ethylmethacrylate]ammoniumbromide (C(16)DMAEMA), and acrylamide (AM) in the presence of α-cyclodextrin (α-CD) using N,N'-methylenebisacrylamide (MBA) as a crosslinker. XRD, solid state (13)C NMR, and DSC measurements show that the crystalline domains, induced by the hydrogen bonds between α-CDs threaded on the hydrophobic units of the polymer chains through the host-guest approach, can reversibly melt and crystallize at different temperatures. Rheological measurements show that both the elastic modulus G' and viscous modulus G'' drastically change due to the formation and dissolution of the crystalline domains. These thermo-sensitive crystalline domains serve as reversible physical crosslinks, endowing the hydrogel with excellent SM properties. Cyclic experiments show that the hydrogel can recover to almost 100% of the deformation in each cycle and can be reused several times.


Assuntos
Acrilamida/química , Resinas Acrílicas/química , Resinas Acrílicas/síntese química , Metacrilatos/química , alfa-Ciclodextrinas/química , Interações Hidrofóbicas e Hidrofílicas
4.
Soft Matter ; 10(7): 972-7, 2014 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-24983105

RESUMO

A novel ferric-phosphate induced shape memory (SM) hydrogel is prepared by the one-step copolymerization of isopropenyl phosphonic acid (IPPA) and acrylamide (AM) in the presence of a crosslinker polyethylene glycol diacrylate (PEGDA). Different from the traditional SM hydrogels, our SM hydrogel can be processed into various shapes as needed and recovers to its original form in 'multiconditions' such as in the presence of a reducing agent or in the presence of a competitive complexing agent. This unique feature is attributed to the fact that the oxidized ferric ions show a high complexation ability with phosphate groups of IPPA, which acts as a physical crosslinker to form the secondary networks within the hydrogels to induce the shape memory effect. The memory behavior was totally reversible, owing to Fe3+ that can be reduced to Fe2+ and extracted by the complexing agent. Particularly, the SM hydrogels exhibit controllable and good mechanical characteristics by introduction of the ferric ions, i.e., the elastic modulus can increase from 2 kPa to 70 kPa dramatically. Learning from biological systems, phosphate-metal ion based hydrogels could become an attractive candidate for various biomedical and environmental applications.


Assuntos
Hidrogéis/síntese química , Ferro/química , Acrilamida/química , Reagentes para Ligações Cruzadas/química , Hidrogéis/química , Iodobenzenos/química , Fosfatos/química , Polietilenoglicóis
5.
Sheng Wu Gong Cheng Xue Bao ; 25(12): 1784-8, 2009 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-20352952

RESUMO

Yeast surface display involves that the exogenous protein, which was fused with the yeast outer shell cell wall protein, was genetically anchored on the yeast cell surface. It has been widely used in expression and screening of functional protein. Here, we focused on the construction of lipase-displaying systems and its application in enzymatic biosynthesis, such as fatty acid methyl esters, short-chain flavour esters and sugar esters applications, and so on.


Assuntos
Lipase/biossíntese , Leveduras/enzimologia , Candida/enzimologia , Candida/genética , Lipase/genética , Pichia/enzimologia , Pichia/genética , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética , Solventes , Leveduras/genética
6.
Zhonghua Yi Xue Za Zhi ; 87(41): 2914-8, 2007 Nov 06.
Artigo em Chinês | MEDLINE | ID: mdl-18261306

RESUMO

OBJECTIVE: To investigate induction of apoptosis of human ovarian cancer CoC1 cells by 5-Allyl-7-Gen-Difluoromethylenechrysin (ADFMChR) in vitro, and its molecular mechanism. METHODS: The proliferative inhibition of CoC1 cells treated with ADFMChR was measured using (3, 4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) colorimetric assay. The apoptosis of CoC1 cells induced by ADFMChR was determined by DNA agarose gel electrophoresis assay and flow cytometry using PI staining. Effect of ADFMChR on PPARgamma, NF-kappaB, Bcl-2, Bax protein expression level of CoC1 cells was detected by Western blotting. RESULTS: The proliferation of CoC1 cells could be significantly inhibited by ADFMChR in a dose-dependent manner, The IC(50) was 7.76 micromol/L. ADFMChR significantly induced apoptosis in a concentration-dependent, the rate of apoptosis was 33.07% and 73.70% respectively after treatment with 10.0, 30.0 micromol/L of ADFMChR for 48 h, which was higher than either the control group (21.70%, 40.00%) at the same concentration ChR-treated cells. The ladder-shaped band could be shown in DNA agarose gel electrophoresis after treatment with ADFMChR at 30.0 micromol/L for 48 h and the ladder-shape band disappeared with GW9662. Western Blot analysis shown that expression of PPARgamma and Bax proteins were upregulation and protein levels of NF-kappaB and Bcl-2 were depress after treatment with ADFMChR in a concentration-dependent. CONCLUSION: The effect of ADFMChR on induction of apoptosis in CoC1 cells may be mediated by activation of PPARgamma, sequentially accompanied by reducing of protein levels of NF-kappaB and Bcl-2 and increasing of Bax expression.


Assuntos
Apoptose/efeitos dos fármacos , Flavonoides/farmacologia , PPAR gama/metabolismo , Western Blotting , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Colorimetria , Relação Dose-Resposta a Droga , Feminino , Flavonoides/química , Citometria de Fluxo , Humanos , NF-kappa B/biossíntese , Neoplasias Ovarianas/metabolismo , Neoplasias Ovarianas/patologia , Proteínas Proto-Oncogênicas c-bcl-2/biossíntese
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