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1.
J Chromatogr A ; 1620: 460972, 2020 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-32106967

RESUMO

This paper reports for the first time the coupling of a two-dimensional separation technique known as orthogonal pressurised planar electrochromatography (OPPEC) with on-line UV/VIS detection. It establishes the efficiency characteristic of a planar column used in OPPEC. The studies show that in OPPEC, all separation steps (mixture introduction, separation, and detection) can run successfully as non-separate operation, much like in HPLC, and the planar column has itself good efficiency, ensuring a relatively low plate height value. In its use, some findings of the previously proposed theoretical model concerning optimisation of preparative separation of components with the same electrophoretic mobility are verified - showing that there is a good agreement between theory and experiment. The paper also demonstrates by means of a specific example of separation of a post-reaction mixture obtained after synthesis of valine diastereomers that OPPEC can be a powerful tool used in preparative separation in that it can achieve much higher separation productivity and significantly lower eluent consumption than when using column chromatography techniques.


Assuntos
Cromatografia/métodos , Eletroforese/métodos , Estereoisomerismo
2.
Int J Artif Organs ; 43(2): 127-136, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32000591

RESUMO

INTRODUCTION: The aim of this study was to develop a novel decellularization method in order to obtain an ideal scaffold with good biocompatibility. METHODS: The porcine corneas were treated with human serum for 5 days or serum-electrophoresis respectively. The electrophoresis (100 V/cm) was performed in sterilized buffer containing 40-mM tris base, 18-mM glacial acetic acid, and antibiotics for 1 h at 4°C. The properties of artificial corneal scaffolds were characterized by morphological and histological examinations. The biocompatibility and biological safety were examined by subcutaneous implant test and lamellar keratoplasty. RESULTS AND CONCLUSIONS: The transparency and appearance of serum-electrophoresis acellular porcine corneal matrix were better than serum acellular porcine corneal matrix. DNA and α-gal in serum-electrophoresis acellular porcine corneal matrix were more efficiently removed than those in serum acellular porcine corneal matrix (p < 0.05). The subcutaneous and corneal implantation experiments showed serum-electrophoresis acellular porcine corneal matrix had better biocompatibility compared to serum acellular porcine corneal matrix (p < 0.01). This novel serum-electrophoresis decellularization method may be valuable for preparation of xenogenic corneal tissue for clinical application.


Assuntos
Materiais Biocompatíveis , Córnea , Transplante de Córnea/métodos , Engenharia Tecidual/métodos , Tecidos Suporte , Animais , Córnea/citologia , Córnea/cirurgia , Eletroforese/métodos , Humanos , Teste de Materiais/métodos , Suínos
3.
Allergol. immunopatol ; 48(1): 26-33, ene.-feb. 2020. ilus, graf
Artigo em Inglês | IBECS | ID: ibc-186588

RESUMO

Introduction and Objectives: The production and consumption of oysters is increasing annually because it can provide essential nutrients and benefit for human health, leading to frequent occurrence of severe allergic reactions observed in sensitized individuals. The aim of the present study was to investigate the effects of acid and protease treatment on the conformation and IgE-binding capacity of recombinant Crassostrea gigas tropomyosin (Cra g 1). Results: Under acidic conditions, Cra g 1 did not undergo degradation, however, the changes obvious in the intensity of CD signal and ANS-binding fluorescence were observed, which was associated with a decrease in antibody reactivity. In simulated gastrointestinal fluid (SGF) and simulated intestinal fluid (SIF) digestion system, acid-treated Cra g 1 was relatively resistant to digestion, but the degradative patterns were very different. Moreover, owing to alterations of secondary structure and hydrophobic surface of the protein during digestive processing, antigenicity of acid-induced Cra g 1 reduced in SGF while it increased significantly in SIF. Conclusion: To our knowledge, this is the first study reporting that antigenicity of acid-treated oyster tropomyosin increased after SIF digestion. These results revealed that treatment with acid and pepsin, rather than trypsin, was an effective way of reducing IgE-binding capacity of tropomyosin from oyster


No disponible


Assuntos
Humanos , Imunoglobulina E/imunologia , Técnicas In Vitro/métodos , Alérgenos/química , Tropomiosina/química , Hipersensibilidade Alimentar/imunologia , Digestão , Alérgenos/imunologia , Tropomiosina/imunologia , Ostreidae/imunologia , Sistema Digestório/imunologia , Eletroforese/métodos , Análise Espectral/métodos , Ensaio de Imunoadsorção Enzimática
4.
Pharm Res ; 37(2): 22, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31897766

RESUMO

PURPOSE: The work aimed to compare quality of a siRNA carrier prepared with chitosan of two different sources having similar degree of deacetylation and molecular weights. Differences were analyzed from thermodynamic characteristics of interactions with siRNA. METHODS: The siRNA carrier (chitosan-coated poly(isobutylcyanoacrylate) nanoparticles) was prepared with home-prepared, CSLab, and commercial, CSCom, chitosans. Chitosan counterion was identified and chitosans CSCommod1 and CSCommod2 were obtained from CSCom exchanging counterion with that found on CSLab. Carrier quality was checked considering the size, zeta potential and siRNA association capacity by gel electrophoresis. Thermodynamic parameters of interactions between siRNA and chitosans in solution or immobilized at the carrier surface were determined by isothermal titration calorimetry (ITC). RESULTS: CSLab and CSCommod2 having a high content of acetate counterion associated better siRNA than CSCom and CSCommod1 which counterion included mainly chloride. ITC measurements indicated that siRNA interactions with chitosan and the siRNA carrier were driven by entropic phenomena including dehydration, but thermodynamic parameters of interactions clearly differed according to the nature of the counterion of chitosan. The influence of chitosan counterions was interpreted considering their different lyotropic character. CONCLUSION: Association of siRNA with our siRNA carrier was influenced by the nature of counterions associated with chitosan. Driven by entropic phenomena including dehydration, interactions were favored by acetate counterion. Although more work would be needed to decipher the influence of the counterion of chitosan during association with siRNA, it was pointed out as a new critical attribute of chitosan to consider while formulating siRNA carrier with this polysaccharide.


Assuntos
Quitosana/química , RNA Interferente Pequeno/química , Calorimetria/métodos , Eletroforese/métodos , Nanopartículas/química , Termodinâmica
5.
J Chromatogr A ; 1610: 460595, 2020 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-31606156

RESUMO

We discuss several possible phenomena in electrophoretic systems with complexing agents present in the background electrolyte. In our previous work, we extended the linear theory of electromigration with the first-order nonlinear term, which originally applied to acid-base equilibria only, by generalizing it to any fast chemical equilibria. This extension provides us with a fresh insight into the well-established technique of elecktrokinetic chromatography (EKC). We combine mathematical analysis of the generalized model with its solution by means of the new version of our software PeakMaster 6, and experimental data. We re-examine the fundamental equations by Wren and Rowe and Tiselius in the frame of the generalized linear theory of electromigration. Besides, we show that selector concentration can increase inside the interacting-analyte zone due to its complexation with the analyte, which contradicts the generally accepted idea of a consumption of a portion of the selector inside the zone. Next, we focus our discussion on interacting buffers (i.e., buffer constituents that form a complex with the selector). We demonstrate how such side-interaction of the selector with another buffer constituent can influence measuring analyte-selector interactions. Finally, we describe occurrence and mobilities of system peaks in these EKC systems. We investigate systems with fully charged analytes and neutral cyclodextrins as selectors. Although the theory is not limited in terms of the charge and/or the degree of (de)protonation of any constituent, this setup allows us to find analytical solutions to generalized model under approximate, yet realistic, conditions and to demonstrate all important phenomena that may occur in EKC systems. An occurrence of system peaks in a system with fully charged selector is also investigated.


Assuntos
Eletroforese Capilar/métodos , Eletroforese/métodos , Tampões (Química) , Ciclodextrinas/química , Eletrólitos/química , Modelos Lineares , Software , Estereoisomerismo
6.
Sensors (Basel) ; 19(23)2019 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-31810237

RESUMO

Dielectrophoresis is an electric force experienced by particles subjected to non-uniform electric fields. Recently, several technologies have been developed focused on the use of dielectrophoretic force (DEP) to manipulate and detect cells. On the other hand, there is no such great development in the field of DEP-based cell discrimination methods. Despite the demand for methods to differentiate biological cell states, most DEP developed methods have been focused on differentiation through geometric parameters. The novelty of the present work relies upon the point that a DEP force cell measurement is used as a discrimination method, capable of detecting heat killed yeast cells from the alive ones. Thermal treatment is used as an example of different biological state of cells. It comes from the fact that biological properties have their reflection in the electric properties of the particle, in this case a yeast cell. To demonstrate such capability of the method, 279 heat-killed cells were measured and compared with alive cells data from the literature. For each cell, six speeds were taken at different points in its trajectory inside a variable non-uniform electric field. The electric parameters in cell wall conductivity, cell membrane conductivity, cell membrane permittivity of the yeast cell from bibliography explains the DEP experimental force measured. Finally, alive and heat-treated cells were distinguished based on that measure. Our results can be explained through the well-known damage of cell structure characteristics of heat-killed cells.


Assuntos
Eletroforese/métodos , Membrana Celular/metabolismo , Eletroquímica , Leveduras/metabolismo
7.
Ars pharm ; 60(4): 219-225, oct.-dic. 2019. graf
Artigo em Espanhol | IBECS | ID: ibc-188485

RESUMO

Introducción: Uno de los fármacos de primera línea en el tratamiento de la esquistosomiasis es el Praziquantel. Numerosas son las formas farmacéuticas sólidas orales desarrolladas hasta la fecha, siendo éstas poco adecuadas para determinados grupos de población, ej. tercera edad y Pediatría, y Veterinaria. Este trabajo describe los primeros pasos en el desarrollo de un estudio de preformulación dirigido al diseño de una forma farmacéutica líquida de administración oral para este principio activo. Método: Se caracterizó la forma y tamaño de las partículas de Praziquantel con las que se pretendía preparar una suspensión acuosa, mediante microscopía electrónica de barrido. Además, se analizó el efecto que el pH y el tipo de electrolito y su concentración tenían sobre el comportamiento de las suspensiones formuladas, gracias a medidas de electroforesis (potencial zeta) y espectrofotometría ultravioleta-visible (turbidimetría en función del tiempo). Resultados: La población de partículas de fármaco se caracterizó por una forma acicular y un tamaño micrométrico, con una distribución de tamaños heterogénea. Se comprobó cómo controlando la composición del medio de dispersión, en términos de pH y electrolitos, podía definirse la carga eléctrica superficial de las partículas de fármaco y, así su proceso de sedimentación, obteniéndose el sistema más adecuado para la vía de administración oral (sistema floculado). Conclusiones: Se han definido las condiciones iniciales de formulación de suspensiones acuosas de Praziquantel destinadas a la vía oral. Un control adecuado de la composición de la fase externa resulta fundamental en el establecimiento del mejor sistema (floculado) para esta vía de administración


Introduction: One of the first-line drugs against schistosomiasis is Praziquantel. Up to now, numerous oral solid dosage forms have been developed, being they considered of little help to elder patients, pediatrics, and Veterinary. Initial steps in the development of preformulation studies aiming the design of a Praziquantel liquid pharmaceutical dosage form to be administered orally are described. Method: Size and shape of Praziquantel particles were characterized by scanning electron microscopy. Furthermore, it was investigated the effect of pH and type of electrolyte and its concentration in the aqueous dispersion media on the behaviour of the suspensions. To that aim, electrokinetic determinations (zeta potential) and ultraviolet-visible spectrophotometry measurements (turbidimetry as a function of time) were done. Results: Drug particles were characterized by an acicular shape and a micrometer size (heterogeneous size distribution). It was observed that controlling the composition of the aqueous dispersion media, in terms of pH and electrolytes, helped in defining the surface electrical charge of the drug particles and, thus the sedimentation profile, obtaining the more adequate system for the oral route of drug administration (flocculated system). Conclusions: Initial conditions to formulate aqueous Praziquantel suspensions for the oral route have been defined. An appropriate control of the composition of the external phase of the suspension is a key aspect when establishing the best liquid pharmaceutical system (flocculated) for this administration route


Assuntos
Humanos , Composição de Medicamentos/métodos , Praziquantel/farmacologia , Suspensão Aquosa/métodos , Estabilidade de Medicamentos , Praziquantel/síntese química , Praziquantel/uso terapêutico , Eletroforese/métodos , Sedimentação , Sedimentação/análise , Eletrólitos/farmacologia
9.
Int J Mol Sci ; 20(22)2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31717257

RESUMO

Bcl-xL is an oncogene of which the survival functions are finely tuned by post-translational modifications (PTM). Within the Bcl-2 family of proteins, Bcl-xL shows unique eligibility to deamidation, a time-related spontaneous reaction. Deamidation is still a largely overlooked PTM due to a lack of easy techniques to monitor Asn→Asp/IsoAsp conversions or Glu→Gln conversions. Being able to detect PTMs is essential to achieve a comprehensive description of all the regulatory mechanisms and functions a protein can carry out. Here, we report a gel composition improving the electrophoretic separation of deamidated forms of Bcl-xL generated either by mutagenesis or by alkaline treatment. Importantly, this new gel formulation proved efficient to provide the long-sought evidence that even doubly-deamidated Bcl-xL remains eligible for regulation by phosphorylation.


Assuntos
Eletroforese/métodos , Processamento de Proteína Pós-Traducional , Proteína bcl-X/metabolismo , Células HCT116 , Humanos , Proteínas Mutantes/isolamento & purificação , Mutação/genética , Fosforilação
10.
Eur. j. anat ; 23(6): 393-403, nov. 2019. graf, ilus, tab
Artigo em Inglês | IBECS | ID: ibc-185082

RESUMO

Hepatitis C is a widely distributed problem all over the world, especially Egypt. Chronically infected people develop serious liver disease and now it is the most common cause for liver transplantation. Recently, a new regimen, sofosbuvir (sovaldi), alone or with combinations as sovaldi-ribavirin, was approved for treating this disease. There are limited studies that explore the effects of these drugs on the reproductive organs, and hence affection of male fertility while using these drugs. This study aims to throw more light on whether sovaldi or sovaldi-ribavirin causes testicular damaging effects in the adult male albino rats. We investigated the effect of this regimen in a dose equivalent to that used in the human (41 mg/kg once daily orally for sovaldi and 41 mg/kg twice daily orally for ribavirin) for consecutive 5 and 10 days. There was highly significant decrease in testosterone hormone level and marked degenerative changes in the seminiferous tubules and the testicular interstitium, with increase in collagen deposits in sovaldi treated rats, and in a more extensive manner in sovaldi-ribavirin treated rats. There was a significant increase of deoxyribonucleic acid (DNA) fragmentation in the treated groups after 10 days. However, there was a non-significant difference in DNA fragmentation in the treated groups after 5 days when compared with control. Immuno-histochemistry detection of caspase-3 showed significant increase in its expression in the treated groups after either 5 or 10 days. This denoted the specificity of caspase-3 immunohistochemistry technique in the detection of early apoptotic changes. It was concluded that sovaldi and sovaldi ribavirin induced gonado toxic effects through induction of DNA fragmentation via up regulation of caspase-3, and that the resulting damaging effects increased with longer duration of drug in take


No disponible


Assuntos
Animais , Ratos , Sofosbuvir/administração & dosagem , Hepatite C/induzido quimicamente , Hepatite C/veterinária , Testículo/efeitos dos fármacos , Ribavirina/administração & dosagem , Disruptores Endócrinos/administração & dosagem , Sofosbuvir/toxicidade , Imuno-Histoquímica , Projetos de Pesquisa , Eletroforese/métodos
11.
Artigo em Inglês | MEDLINE | ID: mdl-31605597

RESUMO

Nanotechnology presents a modern field of science that in the last twenty-five years plays a dominant role in the biomedicine. Different analytical methods are used for evaluation of the physico-chemical properties of nanoparticles including chromatography, electrophoresis, X-ray scattering, spectroscopy, mass spectrometry, zeta potential measurement and microscopy on which this article will focus. Herein, we present novel application of the long-established TEM technique that is focused on characterization and evaluation of various nanoparticles in development of drug delivery systems. Transmission electron microscopy images were taken of samples from native nanoparticles, nanoparticles labeled using stannous chloride labeling procedure, inorganic silica nanoparticles loaded with budesonide and native micelles and micelles carrier of anticancer drug camptothecin. In the case of radiolabeled nanoparticles, beside for nanoparticle characterization, TEM technique was used to confirm the stability of the nanoparticles after radiolabeling. Furthermore, the porous structure of hybrid silica particles loaded with budesonide was examined under TEM. Transmission electron microscopy technique offers exceptional benefits for nanoparticle characterization. Additionally, the necessity of ultrastructural analysis demonstrates the potential of TEM in the field of nanomedicine. Hence, the long-established and well-known TEM has been only partially exploited and offer researchers very detailed images of specimens at microscopic and nano scale.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Microscopia Eletrônica de Transmissão/instrumentação , Nanopartículas/ultraestrutura , Antineoplásicos Fitogênicos/administração & dosagem , Antineoplásicos Fitogênicos/uso terapêutico , Budesonida/administração & dosagem , Budesonida/uso terapêutico , Camptotecina/administração & dosagem , Camptotecina/uso terapêutico , Cromatografia/métodos , Eletroforese/métodos , Glucocorticoides/administração & dosagem , Glucocorticoides/uso terapêutico , Humanos , Espectrometria de Massas/métodos , Microscopia Eletrônica de Transmissão/métodos , Nanopartículas/química , Espalhamento de Radiação , Análise Espectral/métodos
12.
Sensors (Basel) ; 19(17)2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31484453

RESUMO

Dielectrophoretic force is an electric force experienced by particles subjected to non-uniform electric fields. In recent years, plenty of dielectrophoretic force (DEP) applications have been developed. Most of these works have been centered on particle positioning and manipulation. DEP particle characterization has been left in the background. Likewise, these characterizations have studied the electric properties of particles from a qualitative point of view. This article focuses on the quantitative measurement of cells' dielectric force, specifically yeast cells. The measures are obtained as the results of a theoretical model and an instrumental method, both of which are developed and described in the present article, based on a dielectrophoretic chamber made of two V-shaped placed electrodes. In this study, 845 cells were measured. For each one, six speeds were taken at different points in its trajectory. Furthermore, the chamber design is repeatable, and this was the first time that measurements of dielectrophoretic force and cell velocity for double yeast cells were accomplished. To validate the results obtained in the present research, the results have been compared with the dielectric properties of yeast cells collected in the pre-existing literature.


Assuntos
Eletroforese/métodos , Modelos Teóricos
13.
Biosensors (Basel) ; 9(3)2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31394810

RESUMO

This paper presents focusing of microparticles in multiple paths within the direction of the flow using dielectrophoresis. The focusing of microparticles is realized through partially perforated electrodes within the microchannel. A continuous electrode on the top surface of the microchannel is considered, while the bottom side is made of a circular meshed perforated electrode. For the mathematical model of this microfluidic channel, inertia, buoyancy, drag and dielectrophoretic forces are brought up in the motion equation of the microparticles. The dielectrophoretic force is accounted for through a finite element discretization taking into account the perforated 3D geometry within the microchannel. An ordinary differential equation is solved to track the trajectories of the microparticles. For the case of continuous electrodes using the same mathematical model, the numerical simulation shows a very good agreement with the experiments, and this confirms the validation of focusing of microparticles within the proposed perforated electrode microchannel. Microparticles of silicon dioxide and polystyrene are used for this analysis. Their initial positions and radius, the Reynolds number, and the radius of the pore in perforated electrodes mainly conduct microparticles trajectories. Moreover, the radius of the pore of perforated electrode is the dominant factor in the steady state levitation height.


Assuntos
Microfluídica/métodos , Modelos Teóricos , Técnicas Biossensoriais , Eletrodos , Eletroforese/métodos , Microfluídica/instrumentação , Tamanho da Partícula , Poliestirenos/análise , Dióxido de Silício/análise
14.
Chemosphere ; 235: 113-125, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31255751

RESUMO

Electrokinetics is being applied in combination with common insituremediation technologies, e.g. permeable reactive barriers, bioremediation and in-situ chemical oxidation, to overcome experienced limitations in remediation of chlorinated ethenes in low-permeable subsurface soils. The purpose of this review is to evaluate state-of-theart for identification of major knowledge gaps to obtain robust and successful field-implementations. Some of the major knowledge gaps include the behavior and influence of induced transient changes in soil systems, transport velocities of chlorinated ethenes, and significance of site-specific parameters on transport velocities, e.g. heterogeneous soils and hydrogeochemistry. Furthermore, the various ways of reporting voltage distribution and transport rates complicate the comparison of transport velocities across studies. It was found, that for the combined EK-techniques, it is important to control the pH and redox changes caused by electrolysis for steady transport, uniform distribution of the electric field etc. Specifically for electrokinetically enhanced bioremediation, delivery of lactate and biodegrading bacteria is of the same order of magnitude. This review shows that enhancement of remediation technologies can be achieved by electrokinetics, but major knowledge gaps must be examined to mature EK as robust methods for successful remediation of chlorinated ethene contaminated sites.


Assuntos
Eletroforese/métodos , Recuperação e Remediação Ambiental/métodos , Etilenos/análise , Hidrocarbonetos Clorados/análise , Poluentes do Solo/análise , Solo/química , Bactérias/metabolismo , Biodegradação Ambiental , Oxirredução
15.
Biofabrication ; 11(4): 045017, 2019 08 22.
Artigo em Inglês | MEDLINE | ID: mdl-31315102

RESUMO

This work reports an important new development in the production of collagen membranes, based on pulsed electrophoretic deposition (P-EPD), suitable for a wide range of biomedical applications. Collagen membranes are of great interest as a biomaterial and in a range of other industries, though current production techniques suffer from limitations with scaling up, homogeneity, and complex shapes. P-EPD can be used to rapidly create detachable, large-area, homogeneous products with controlled thickness in a wide variety of shapes. We provide a new understanding of the influence of a range of parameters (pulse width, voltage, duty cycle, solvent additions) and their effects on membrane structure. Characterisation by AFM, SEM, and cryoSEM revealed the ability to produce dense, structurally defect-free membranes, and significantly, we show and discuss the ability to produce thicker membranes by sequential deposition without seeing a corresponding increase in cell electrical resistance. We anticipate this novel, rapid, and controllable method for the production of collagen membranes to be of interest for a wide range of fields.


Assuntos
Colágeno/química , Eletroforese/métodos , Membranas Artificiais , Animais , Bovinos , Hidrogéis/química , Imageamento Tridimensional , Solventes , Eletricidade Estática
16.
Anal Bioanal Chem ; 411(23): 5951-5962, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31280479

RESUMO

(Bio-)nanoparticle analysis employing a nano-electrospray gas-phase electrophoretic mobility molecular analyzer (native nES GEMMA) also known as nES differential mobility analyzer (nES DMA) is based on surface-dry analyte separation at ambient pressure. Based on electrophoretic principles, single-charged nanoparticles are separated according to their electrophoretic mobility diameter (EMD) corresponding to the particle size for spherical analytes. Subsequently, it is possible to correlate the (bio-)nanoparticle EMDs to their molecular weight (MW) yielding a corresponding fitted curve for an investigated analyte class. Based on such a correlation, (bio-)nanoparticle MW determination via its EMD within one analyte class is possible. Turning our attention to icosahedral, non-enveloped virus-like particles (VLPs), proteinaceous shells, we set up an EMD/MW correlation. We employed native electrospray ionization mass spectrometry (native ESI MS) to obtain MW values of investigated analytes, where possible, after extensive purification. We experienced difficulties in native ESI MS with time-of-flight (ToF) detection to determine MW due to sample inherent characteristics, which was not the case for charge detection (CDMS). nES GEMMA exceeds CDMS in speed of analysis and is likewise less dependent on sample purity and homogeneity. Hence, gas-phase electrophoresis yields calculated MW values in good approximation even when charge resolution was not obtained in native ESI ToF MS. Therefore, both methods-native nES GEMMA-based MW determination via an analyte class inherent EMD/MW correlation and native ESI MS-in the end relate (bio-)nanoparticle MW values. However, they differ significantly in, e.g., ease of instrument operation, sample and analyte handling, or costs of instrumentation. Graphical abstract.


Assuntos
Eletroforese/métodos , Espectrometria de Massas por Ionização por Electrospray/métodos , Vacinas de Partículas Semelhantes a Vírus/química , Vírus/química , Peso Molecular , Tamanho da Partícula , Proteínas/química , Vírion/química
17.
Int J Mol Sci ; 20(14)2019 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-31340481

RESUMO

We employed dielectrophoresis to a yeast cell suspension containing amyloid-beta proteins (Aß) in a microfluidic environment. The Aß was separated from the cells and characterized using the gradual dissolution of Aß as a function of the applied dielectrophoretic parameters. We established the gradual dissolution of Aß under specific dielectrophoretic parameters. Further, Aß in the fibril form at the tip of the electrode dissolved at high frequency. This was perhaps due to the conductivity of the suspending medium changing according to the frequency, which resulted in a higher temperature at the tips of the electrodes, and consequently in the breakdown of the hydrogen bonds. However, those shaped as spheroidal monomers experienced a delay in the Aß fibril transformation process. Yeast cells exposed to relatively low temperatures at the base of the electrode did not experience a positive or negative change in viability. The DEP microfluidic platform incorporating the integrated microtip electrode array was able to selectively manipulate the yeast cells and dissolve the Aß to a controlled extent. We demonstrate suitable dielectrophoretic parameters to induce such manipulation, which is highly relevant for Aß-related colloidal microfluidic research and could be applied to Alzheimer's research in the future.


Assuntos
Peptídeos beta-Amiloides/isolamento & purificação , Eletroforese/métodos , Técnicas Analíticas Microfluídicas/instrumentação , Saccharomyces cerevisiae/química , Eletrodos , Eletroforese/instrumentação , Liofilização , Ligação de Hidrogênio , Cinética , Saccharomyces cerevisiae/citologia , Solubilidade , Temperatura
18.
Sensors (Basel) ; 19(14)2019 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-31336874

RESUMO

We present a monolithic biosensor platform, based on carbon-nanotube field-effect transistors (CNTFETs), for the detection of the neurotransmitter glutamate. We used an array of 9'216 CNTFET devices with 96 integrated readout and amplification channels that was realized in complementary metal-oxide semiconductor technology (CMOS). The detection principle is based on amperometry, where electrochemically active hydrogen peroxide, a product of the enzymatic reaction of the target analyte and an enzyme that was covalently bonded to the CNTFET, modulated the conductance of the CNTFET-based sensors. We assessed the performance of the CNTs as enzymatic sensors by evaluating the minimal resolvable concentration change of glutamate in aqueous solutions. The minimal resolvable concentration change amounted to 10 µM of glutamate, which was one of the best values reported for CMOS-based systems so far.


Assuntos
Aminoácido Oxirredutases/química , Técnicas Biossensoriais/instrumentação , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Ácido Glutâmico/análise , Nanotubos de Carbono/química , Calibragem , Eletrodos , Eletroforese/instrumentação , Eletroforese/métodos , Desenho de Equipamento , Concentração de Íons de Hidrogênio , Neurotransmissores/análise , Semicondutores , Sensibilidade e Especificidade , Soluções/química , Água/química
19.
Electrophoresis ; 40(20): 2718-2727, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31206722

RESUMO

Microelectrode arrays are used to sort single fluorescently labeled cells and particles as they flow through a microfluidic channel using dielectrophoresis. Negative dielectrophoresis is used to create a "Dielectrophoretic virtual channel" that runs along the center of the microfluidic channel. By switching the polarity of the electrodes, the virtual channel can be dynamically reconfigured to direct particles along a different path. This is demonstrated by sorting particles into two microfluidic outlets, controlled by an automated system that interprets video data from a color camera and makes complex sorting decisions based on color, intensity, size, and shape. This enables the rejection of particle aggregates and other impurities, and the system is optimized to isolate high purity populations from a heterogeneous sample. Green beads are isolated from an excess of red beads with 100% purity at a rate of up to 0.9 particles per second, in addition application to the sorting of osteosarcoma and human bone marrow cells is evidenced. The extension of Dielectrophoretic Virtual Channels to an arbitrary number of sorting outputs is examined, with design, simulation, and experimental verification of two alternate geometries presented and compared.


Assuntos
Separação Celular , Eletroforese , Processamento de Imagem Assistida por Computador/métodos , Técnicas Analíticas Microfluídicas/instrumentação , Linhagem Celular Tumoral , Separação Celular/instrumentação , Separação Celular/métodos , Eletroforese/instrumentação , Eletroforese/métodos , Desenho de Equipamento , Humanos , Tamanho da Partícula
20.
Electrophoresis ; 40(20): 2728-2735, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31219180

RESUMO

This paper presents the development and experimental analysis of a curved microelectrode platform for the DEP deformation of breast cancer cells (MDA-MB-231). The platform is composed of arrays of curved DEP microelectrodes which are patterned onto a glass slide and samples containing MDA-MB-231 cells are pipetted onto the platform's surface. Finite element method is utilised to characterise the electric field gradient and DEP field. The performance of the system is assessed with MDA-MB-231 cells in a low conductivity 1% DMEM suspending medium. We applied sinusoidal wave AC potential at peak to peak voltages of 2, 5, and 10 Vpp at both 10 kHz and 50 MHz. We observed cell blebbing and cell shrinkage and analyzed the percentage of shrinkage of the cells. The experiments demonstrated higher percentage of cell shrinkage when cells are exposed to higher frequency and peak to peak voltage electric field.


Assuntos
Neoplasias da Mama/patologia , Membrana Celular/fisiologia , Forma Celular/fisiologia , Eletroforese/instrumentação , Linhagem Celular Tumoral , Eletroforese/métodos , Feminino , Humanos , Microeletrodos
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