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Pesquisa : D02.455.326.146.100.250 [Categoria DeCS]
Referências encontradas : 647 [refinar]
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[PMID]:27993432
[Au] Autor:Xu X; Gevaert B; Bracke N; Yao H; Wynendaele E; De Spiegeleer B
[Ad] Endereço:Drug Quality and Registration (DruQuaR) Group, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, B-9000 Ghent, Belgium.
[Ti] Título:Hydrophilic interaction liquid chromatography method development and validation for the assay of HEPES zwitterionic buffer.
[So] Source:J Pharm Biomed Anal;135:227-233, 2017 Feb 20.
[Is] ISSN:1873-264X
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:HEPES is a zwitterionic buffer component used as a raw material in the GMP-manufacturing of advanced therapy medicinal products (ATMPs), hence requiring an adequate assay method with sufficient selectivity toward related impurities. Therefore, a hydrophilic interaction chromatography (HILIC) method was developed. Different factors were investigated towards the retention behavior of HEPES, its analogue EPPS and its starting material isethionate: pH, ion concentration and organic solvent ratio of the mobile phase, as well as column temperature. Moreover, stress testing resulted in the N-oxide degradant, identified by high resolution MS. The final method consisted of an isocratic system with an aqueous (pH 2.0 with H PO ) acetonitrile (35:65, v/v) mobile phase on a zwitterionic HILIC (Obelisc N) column with a flow rate of 0.5mL/min and UV detection at 195nm. The assay method of HEPES was validated, obtaining adequate linearity (R =0.999), precision (RSD of 0.5%) and accuracy (recovery of 100.08%). Finally, the applicability of the validated method was demonstrated by analysis of samples from different suppliers.
[Mh] Termos MeSH primário: Química Farmacêutica/métodos
Química Farmacêutica/normas
HEPES/análise
Interações Hidrofóbicas e Hidrofílicas
[Mh] Termos MeSH secundário: Tampões (Química)
Cromatografia Líquida/métodos
Cromatografia Líquida/normas
Concentração de Íons de Hidrogênio
Reprodutibilidade dos Testes
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Buffers); RWW266YE9I (HEPES)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170524
[Lr] Data última revisão:
170524
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161221
[St] Status:MEDLINE


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[PMID]:27424309
[Au] Autor:Moriwaki H; Yamada K; Usami H
[Ad] Endereço:Shinshu University, Faculty of Textile Science and Technology, Division of Applied Biology, 3-15-1, Tokida, Ueda 386-8567, Japan; Shinshu University, Division of Instrumental Analysis (Ueda branch), Research Center for Supports to Advanced Science, 3-15-1, Tokida, Ueda 386-8567, Japan. Electronic address: moriwaki@shinshu-u.ac.jp.
[Ti] Título:Electrochemical extraction of gold from wastes as nanoparticles stabilized by phospholipids.
[So] Source:Waste Manag;60:591-595, 2017 Feb.
[Is] ISSN:1879-2456
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:A simple one-step method for the extraction of gold from wastes as nanoparticles stabilized by phospholipids is demonstrated. This is achieved by applying an AC voltage for 5s to the gold-containing wastes, which act as the electrodes in a buffer solution containing a dispersed phospholipid (1,2-dioleoyl-sn-glycero-3-phosphocholine, DOPC). This is an environmentally friendly and rapid method for recovering gold from wastes. The extracted gold nanoparticles have significant potential as a catalyst or biomedical material.
[Mh] Termos MeSH primário: Técnicas Eletroquímicas/métodos
Ouro/isolamento & purificação
Nanopartículas/química
Fosfolipídeos/química
Gerenciamento de Resíduos/métodos
[Mh] Termos MeSH secundário: Fracionamento Químico/métodos
Resíduo Eletrônico
Ouro/química
HEPES/química
Fosfatidilcolinas/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Phosphatidylcholines); 0 (Phospholipids); 7440-57-5 (Gold); EDS2L3ODLV (1,2-oleoylphosphatidylcholine); RWW266YE9I (HEPES)
[Em] Mês de entrada:1707
[Cu] Atualização por classe:171116
[Lr] Data última revisão:
171116
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160718
[St] Status:MEDLINE


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[PMID]:27169667
[Au] Autor:Suttirojpattana T; Somfai T; Matoba S; Parnpai R; Nagai T; Geshi M
[Ad] Endereço:Embryo Technology and Stem Cell Research Center, Suranaree University of Technology, Nakhon Ratchasima, Thailand.
[Ti] Título:Effect of medium additives during liquid storage on developmental competence of in vitro matured bovine oocytes.
[So] Source:Anim Sci J;88(2):231-240, 2017 Feb.
[Is] ISSN:1740-0929
[Cp] País de publicação:Australia
[La] Idioma:eng
[Ab] Resumo:Our aim was to improve the developmental competence of bovine oocytes during their liquid storage by using additives. In vitro matured oocytes were stored for 20 h at 25°C in HEPES buffered TCM 199 medium (base medium). After storage, in vitro embryo development after in vitro fertilization was compared to those of non-stored (control) ones. Addition of 10% (v/v) newborn calf serum or 10.27 mmol/L pyruvate alone to the base medium did not improve blastocyst formation rates in stored oocytes; however, their simultaneous addition significantly improved the rate compared with those stored in base medium (P < 0.05). Supplementation of the holding medium with dithiothreitol (DTT) at any concentrations did not improve embryo development from stored oocytes. Although supplementation with cyclosporine A (CsA) significantly reduced apoptosis and membrane damage rates during storage, it did not improve the developmental competence of oocytes. 1,2-bis(2-aminophenoxy) ethane N,N,N',N'-tetraacetic acid tetrakis-acetoxymethyl ester and ruthenium red had no effect on oocyte apoptotic rates. Blastocyst formation rates in all stored groups remained significantly lower than that of the control. In conclusion, pyruvate and serum had a synergic effect to moderate the reduction of oocyte quality during storage, whereas mitochondrial membrane pore inhibitor CsA and the antioxidant DTT did not affect their developmental competence.
[Mh] Termos MeSH primário: Meios de Cultura/farmacologia
Fertilização In Vitro/métodos
Oócitos/crescimento & desenvolvimento
[Mh] Termos MeSH secundário: Animais
Bovinos
Células Cultivadas
Ciclosporina/farmacologia
Ditiotreitol/farmacologia
Desenvolvimento Embrionário
Feminino
Fertilização In Vitro/efeitos dos fármacos
HEPES
Técnicas In Vitro
Ácido Pirúvico/farmacologia
Soro
Preservação de Tecido
[Pt] Tipo de publicação:COMPARATIVE STUDY; JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Culture Media); 83HN0GTJ6D (Cyclosporine); 8558G7RUTR (Pyruvic Acid); RWW266YE9I (HEPES); T8ID5YZU6Y (Dithiothreitol)
[Em] Mês de entrada:1703
[Cu] Atualização por classe:170316
[Lr] Data última revisão:
170316
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160513
[St] Status:MEDLINE
[do] DOI:10.1111/asj.12623


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[PMID]:28072433
[Au] Autor:Xu Y; Yu HM; Niu YQ; Luo SC; Cheng X
[Ad] Endereço:Institute of Biothermal Science and Technology, University of Shanghai for Science and Technology, Shanghai, China. xuyi@usst.edu.cn.
[Ti] Título:Effects of Superparamagnetic Nanoparticles on Nucleation and Crystal Growth in the Vitrified VS55 During Warming.
[So] Source:Cryo Letters;37(6):448-454, 2016 Nov/Dec.
[Is] ISSN:0143-2044
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:  BACKGROUND:Magnetic nanoparticles (mNPs), once excited by radiofrequency (RF) energy, could heat uniformly and rapidly the vitrified biospecimens. However, there are few studies about the impact of mNPs on crystallization kinetics of vitrified samples. OBJECTIVES: The present work aims to investigate the nucleation and crystal growth in the vitrification solution VS55 with mNPs. MATERIALS AND METHODS: Ferrotec EMG308 superparamagnetic nanoparticles (10 ± 2.5 nm in diameter) coated with an anionic surfactant was used in this study with Fe2+ concentration around 10 mg/ml. The thermal range and the kinetics of nucleation and crystal growth are conducted by DSC and cryomicroscope through different thermal treatments. RESULTS: The fusion heat of VS55+ mNPs is lower than that of VS55 around the rubbery region (-110 to -82 degree C), which suggests the suppression of ice nuclei formation at this temperature range by mNPs. Upon slow cooling especially, much more nuclei in vitrified VS55 forms than that in vitrified VS55+mNPs. The activation energy E of VS55 is lower than that of VS55+mNPs (41.6 kJ/mol vs 46.2 kJ/mol) during devitrification. The presence of mNPs helps to form more stable glass. And these results are consistent with the observations by cryomicroscope. CONCLUSION: The presence of mNPs suppresses ice nuclei formation, especially at slow cooling conditions, and stabilize the cryoprotective solution. The findings can assist the design of magnetic nanoparticles with functional surface coating.
[Mh] Termos MeSH primário: Criopreservação/métodos
Crioprotetores/farmacologia
Dimetil Sulfóxido/farmacologia
Formamidas/farmacologia
HEPES/farmacologia
Nanopartículas de Magnetita
Propilenoglicóis/farmacologia
Vitrificação
[Mh] Termos MeSH secundário: Cristalização
Cinética
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Cryoprotective Agents); 0 (Formamides); 0 (Magnetite Nanoparticles); 0 (Propylene Glycols); 0 (VS55 solution); RWW266YE9I (HEPES); YOW8V9698H (Dimethyl Sulfoxide)
[Em] Mês de entrada:1706
[Cu] Atualização por classe:170619
[Lr] Data última revisão:
170619
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170111
[St] Status:MEDLINE


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[PMID]:27816225
[Au] Autor:Baeza AN; Urraca JL; Chamorro R; Orellana G; Castellari M; Moreno-Bondi MC
[Ad] Endereço:Department of Analytical Chemistry, Faculty of Chemistry, Universidad Complutense de Madrid, E-28040 Madrid, Spain; Institute of Materials Research and Engineering (IMRE), University of Havana, Havana 10400, Cuba.
[Ti] Título:Multiresidue analysis of cephalosporin antibiotics in bovine milk based on molecularly imprinted polymer extraction followed by liquid chromatography-tandem mass spectrometry.
[So] Source:J Chromatogr A;1474:121-129, 2016 Nov 25.
[Is] ISSN:1873-3778
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:This work reports the preparation of molecularly imprinted polymers (MIPs) selective to cephalosporin (CF) antibiotics, and their application as molecularly imprinted solid-phase extraction (MISPE) sorbents for the determination of these antimicrobials in milk samples. Several functional monomers and cross-linkers have been screened to select the best combination that provides high selectivity for the simultaneous multiresidue extraction of cefthiofur (THIO), cefazolin (AZO), cefquinome (QUI), cephapirin (API), cephalexin (ALE) and cephalonium (ALO) from the samples. The novel MIPs were prepared by a non-covalent imprinting approach in the form of spherical microparticles using the synthetic surrogate molecule sodium 7-(2-biphenylylcarboxamido)-3-methyl-3-cepheme-4-carboxylate, N-3,5-bis(trifluoromethyl)phenyl-N'-4-vinylphenyl urea (VPU) as functional monomer, and divinylbenzene (DVB) as crosslinking agent in a 1:2:20 molar ratio. The optimized MISPE method allowed the extraction of the target antimicrobials from raw cow milk samples using a selective washing with 5mL methanol/2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid (HEPES) buffer (0.1M, pH 7.5) (2:98, v/v) to remove the non-specifically retained compounds, followed by elution with 1mL of trifluoroacetic acid (TFA) in methanol (0.1:99.9, v/v). The extracts have been analysed by UHPLC-MS/MS and the analytical method has been validated according to EU guideline 2002/657/EC. The limits of quantification (S/N=10) were in the 1.7-12.5µgkg range, well below the maximum residue limits (MRLs) currently established for the quantified cephalosporins in milk samples. The developed MIP allows mutiresidual determination of the six cephalosporin antibiotics mentioned above, significantly broadening the application to food analysis of MISPE methods.
[Mh] Termos MeSH primário: Antibacterianos/análise
Cefalosporinas/análise
Resíduos de Drogas/análise
Leite/química
[Mh] Termos MeSH secundário: Animais
Bovinos
Cromatografia Líquida de Alta Pressão
Reagentes para Ligações Cruzadas
HEPES
Metanol
Microscopia Eletrônica de Varredura
Impressão Molecular
Polímeros
Solventes
Espectrometria de Massas em Tandem
Ácido Trifluoracético
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Anti-Bacterial Agents); 0 (Cephalosporins); 0 (Cross-Linking Reagents); 0 (Polymers); 0 (Solvents); E5R8Z4G708 (Trifluoroacetic Acid); RWW266YE9I (HEPES); Y4S76JWI15 (Methanol)
[Em] Mês de entrada:1703
[Cu] Atualização por classe:170817
[Lr] Data última revisão:
170817
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161107
[St] Status:MEDLINE


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[PMID]:27225657
[Au] Autor:Li S; Kim E; Bonanno JA
[Ad] Endereço:School of Optometry, Indiana University, Bloomington, Indiana.
[Ti] Título:Fluid transport by the cornea endothelium is dependent on buffering lactic acid efflux.
[So] Source:Am J Physiol Cell Physiol;311(1):C116-26, 2016 Jul 01.
[Is] ISSN:1522-1563
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Maintenance of corneal hydration is dependent on the active transport properties of the corneal endothelium. We tested the hypothesis that lactic acid efflux, facilitated by buffering, is a component of the endothelial fluid pump. Rabbit corneas were perfused with bicarbonate-rich (BR) or bicarbonate-free (BF) Ringer of varying buffering power, while corneal thickness was measured. Perfusate was collected and analyzed for lactate efflux. In BF with no added HEPES, the maximal corneal swelling rate was 30.0 ± 4.1 µm/h compared with 5.2 ± 0.9 µm/h in BR. Corneal swelling decreased directly with [HEPES], such that with 60 mM HEPES corneas swelled at 7.5 ± 1.6 µm/h. Perfusate [lactate] increased directly with [HEPES]. Similarly, reducing the [HCO3 (-)] increased corneal swelling and decreased lactate efflux. Corneal swelling was inversely related to Ringer buffering power (ß), whereas lactate efflux was directly related to ß. Ouabain (100 µM) produced maximal swelling and reduction in lactate efflux, whereas carbonic anhydrase inhibition and an monocarboxylic acid transporter 1 inhibitor produced intermediate swelling and decreases in lactate efflux. Conversely, 10 µM adenosine reduced the swelling rate to 4.2 ± 0.8 µm/h and increased lactate efflux by 25%. We found a strong inverse relation between corneal swelling and lactate efflux (r = 0.98, P < 0.0001). Introducing lactate in the Ringer transiently increased corneal thickness, reaching a steady state (0 ± 0.6 µm/h) within 90 min. We conclude that corneal endothelial function does not have an absolute requirement for bicarbonate; rather it requires a perfusing solution with high buffering power. This facilitates lactic acid efflux, which is directly linked to water efflux, indicating that lactate flux is a component of the corneal endothelial pump.
[Mh] Termos MeSH primário: Epitélio Posterior/metabolismo
Ácido Láctico/metabolismo
Transportadores de Ácidos Monocarboxílicos/metabolismo
Simportadores/metabolismo
[Mh] Termos MeSH secundário: Animais
Bicarbonatos/metabolismo
Transporte Biológico Ativo
Tampões (Química)
Inibidores da Anidrase Carbônica/farmacologia
Epitélio Posterior/efeitos dos fármacos
Feminino
HEPES/química
Concentração de Íons de Hidrogênio
Técnicas In Vitro
Soluções Isotônicas/metabolismo
Masculino
Modelos Biológicos
Transportadores de Ácidos Monocarboxílicos/antagonistas & inibidores
Perfusão
Coelhos
ATPase Trocadora de Sódio-Potássio/antagonistas & inibidores
ATPase Trocadora de Sódio-Potássio/metabolismo
Simportadores/antagonistas & inibidores
Fatores de Tempo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Bicarbonates); 0 (Buffers); 0 (Carbonic Anhydrase Inhibitors); 0 (Isotonic Solutions); 0 (Monocarboxylic Acid Transporters); 0 (Symporters); 0 (monocarboxylate transport protein 1); 33X04XA5AT (Lactic Acid); 8022-63-7 (Ringer's lactate); EC 3.6.3.9 (Sodium-Potassium-Exchanging ATPase); RWW266YE9I (HEPES)
[Em] Mês de entrada:1706
[Cu] Atualização por classe:170714
[Lr] Data última revisão:
170714
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160527
[St] Status:MEDLINE
[do] DOI:10.1152/ajpcell.00095.2016


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Vergani, Carlos Eduardo
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[PMID]:27060444
[Au] Autor:Dias Kde C; Barbugli PA; Vergani CE
[Ad] Endereço:Department of Dental Materials and Prosthodontics, Oral Rehabilitation Program-Araraquara School of Dentistry, UNESP-Univ. Estadual Paulista, Centro, 14801903 Araraquara, SP, Brazil. Electronic address: kassiaodonto@hotmail.com.
[Ti] Título:Influence of different buffers (HEPES/MOPS) on keratinocyte cell viability and microbial growth.
[So] Source:J Microbiol Methods;125:40-2, 2016 06.
[Is] ISSN:1872-8359
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:This study assessed the effect of the buffers 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) and 3-(N-morpholino) propanesulfonic acid (MOPS) on keratinocyte cell viability and microbial growth. It was observed that RPMI buffered with HEPES, supplemented with l-glutamine and sodium bicarbonate, can be used as a more suitable medium to promote co-culture.
[Mh] Termos MeSH primário: Sobrevivência Celular/efeitos dos fármacos
Meios de Cultura/química
HEPES/farmacologia
Queratinócitos/fisiologia
Morfolinas/farmacologia
Staphylococcus aureus/crescimento & desenvolvimento
[Mh] Termos MeSH secundário: Animais
Biofilmes/efeitos dos fármacos
Biofilmes/crescimento & desenvolvimento
Tampões (Química)
Linhagem Celular
Células Cultivadas
HEPES/química
Seres Humanos
Concentração de Íons de Hidrogênio
Queratinócitos/efeitos dos fármacos
Morfolinas/química
Morfolinas/toxicidade
Staphylococcus aureus/efeitos dos fármacos
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Buffers); 0 (Culture Media); 0 (Morpholines); 273BP63NV3 (morpholinopropane sulfonic acid); RWW266YE9I (HEPES)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:171106
[Lr] Data última revisão:
171106
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160410
[St] Status:MEDLINE


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[PMID]:26997348
[Au] Autor:Xing P; Gao K; Wang B; Gao J; Yan H; Wen J; Li W; Xu Y; Li H; Chen J; Wang W; Sun S
[Ad] Endereço:College of Science, Northwest A&F University, Yangling, Shaanxi 712100, China. sunsg@nwsuaf.edu.cn.
[Ti] Título:HEPES is not suitable for fluorescence detection of HClO: a novel probe for HClO in absolute PBS.
[So] Source:Chem Commun (Camb);52(28):5064-6, 2016 Apr 11.
[Is] ISSN:1364-548X
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:HEPES is not suitable for fluorescence detection of HClO because it can be oxidized by HClO. A novel probe for HClO, which can selectively and sensitively detect HClO in absolute PBS, was developed on the basis of an oxidation reaction with an azo moiety. Furthermore, it works well in live mouse imaging.
[Mh] Termos MeSH primário: Fluorescência
Corantes Fluorescentes/química
Ácido Hipocloroso/análise
Fosfatos/química
[Mh] Termos MeSH secundário: Animais
Tampões (Química)
Corantes Fluorescentes/análise
HEPES/química
Camundongos
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Buffers); 0 (Fluorescent Dyes); 0 (Phosphates); 712K4CDC10 (Hypochlorous Acid); RWW266YE9I (HEPES)
[Em] Mês de entrada:1612
[Cu] Atualização por classe:161230
[Lr] Data última revisão:
161230
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160322
[St] Status:MEDLINE
[do] DOI:10.1039/c6cc00880a


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[PMID]:26936029
[Au] Autor:Kandandapani S; Tan CY; Shuib AS; Tayyab S
[Ti] Título:Influence of Buffer Composition and Calcium Chloride on GdnHCl Denaturation of Bacillus licheniformis α-Amylase.
[So] Source:Protein Pept Lett;23(6):537-43, 2016.
[Is] ISSN:1875-5305
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:The influence of buffer composition on the conformational stability of native and calciumdepleted Bacillus licheniformis α-amylase (BLA) was investigated against guanidine hydrochloride (GdnHCl) denaturation using circular dichroism, fluorescence and UV-difference spectroscopy. Differential effect of buffer composition on GdnHCl denaturation of BLA was evident from the magnitude of these spectral signals, which followed the order: sodium phosphate > Tris-HCl > HEPES > MOPS. These effects became more pronounced with calcium-depleted BLA. Sephacryl S-200 gel chromatographic results showed significant BLA aggregation in the presence of 6 M GdnHCl.
[Mh] Termos MeSH primário: Bacillus licheniformis/enzimologia
Cloreto de Cálcio/química
Guanidina/química
HEPES/química
Morfolinas/química
Fosfatos/química
Fosfinas/química
alfa-Amilases/química
[Mh] Termos MeSH secundário: Tampões (Química)
Dicroísmo Circular
Desnaturação Proteica
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Buffers); 0 (Morpholines); 0 (Phosphates); 0 (Phosphines); 0 (tris(hydroxymethyl)phosphine); 273BP63NV3 (morpholinopropane sulfonic acid); EC 3.2.1.1 (alpha-Amylases); EC 3.2.1.1 (alpha-amylase, Bacillus licheniformis); JU58VJ6Y3B (Guanidine); M4I0D6VV5M (Calcium Chloride); RWW266YE9I (HEPES); SE337SVY37 (sodium phosphate)
[Em] Mês de entrada:1703
[Cu] Atualização por classe:170327
[Lr] Data última revisão:
170327
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160304
[St] Status:MEDLINE


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[PMID]:26837938
[Au] Autor:Trewby W; Livesey D; Voïtchovsky K
[Ad] Endereço:Durham University, Stockton Road, DH1 3LE, UK. kislon.voitchovsky@durham.ac.uk.
[Ti] Título:Buffering agents modify the hydration landscape at charged interfaces.
[So] Source:Soft Matter;12(9):2642-51, 2016 Mar 07.
[Is] ISSN:1744-6848
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:Buffering agents are widely used to stabilise the pH of solutions in soft matter and biological sciences. They are typically composed of weak acids and bases mixed in an aqueous solution, and can interact electrostatically with charged surfaces such as biomembranes. Buffers can induce protein aggregation and structural modification of soft interfaces, but a molecular-level picture is still lacking. Here we use high-resolution atomic force microscopy to investigate the effect of five commonly used buffers, namely 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid (HEPES), 2-(N-morpholino)ethanesulfonic acid (MES), monosodium phosphate, saline sodium citrate (SSC) and tris(hydroxymethyl)aminomethane (Tris) on the hydration landscape of Muscovite mica in solution. Mica is an ideal model substrate due to its negative surface charge and identical lattice parameter when compared with gel-phase lipid bilayers. We show that buffer molecules can produce cohesive aggregates spanning over tens of nanometres of the interface. SSC, Tris and monosodium phosphate tend to create an amorphous mesh layer several molecules thick and with no preferential ordering. In contrast, MES and HEPES adopt epitaxial arrangements commensurate with the underlying mica lattice, suggesting that they offer the most suitable solution for high-resolution studies. To confirm that this effect persisted in biologically-relevant interfaces, the experiments were repeated on a silica-supported lipid bilayer. Similar trends were observed for this system using atomic force microscopy as well as ellipsometry. The effect of the buffering agents can be mitigated by the inclusion of salt which helps displace them from the interface.
[Mh] Termos MeSH primário: Bicamadas Lipídicas/química
[Mh] Termos MeSH secundário: Ácidos Alcanossulfônicos/química
Tampões (Química)
Citratos/química
HEPES/química
Microscopia de Força Atômica
Modelos Moleculares
Conformação Molecular
Morfolinas/química
Fosfatos/química
Dióxido de Silício/química
Trometamina/química
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Alkanesulfonic Acids); 0 (Buffers); 0 (Citrates); 0 (Lipid Bilayers); 0 (Morpholines); 0 (Phosphates); 023C2WHX2V (Tromethamine); 1Q73Q2JULR (sodium citrate); 2GNK67Q0C4 (2-(N-morpholino)ethanesulfonic acid); 7631-86-9 (Silicon Dioxide); RWW266YE9I (HEPES)
[Em] Mês de entrada:1610
[Cu] Atualização por classe:161230
[Lr] Data última revisão:
161230
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160204
[St] Status:MEDLINE
[do] DOI:10.1039/c5sm02445e



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