Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.625
Filtrar
1.
Nat Commun ; 11(1): 657, 2020 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-32005876

RESUMO

To advance microfluidic integration, we present the use of two-photon additive manufacturing to fold 2D channel layouts into compact free-form 3D fluidic circuits with nanometer precision. We demonstrate this technique by tailoring microfluidic nozzles and mixers for time-resolved structural biology at X-ray free-electron lasers (XFELs). We achieve submicron jets with speeds exceeding 160 m s-1, which allows for the use of megahertz XFEL repetition rates. By integrating an additional orifice, we implement a low consumption flow-focusing nozzle, which is validated by solving a hemoglobin structure. Also, aberration-free in operando X-ray microtomography is introduced to study efficient equivolumetric millisecond mixing in channels with 3D features integrated into the nozzle. Such devices can be printed in minutes by locally adjusting print resolution during fabrication. This technology has the potential to permit ultracompact devices and performance improvements through 3D flow optimization in all fields of microfluidic engineering.


Assuntos
Microfluídica/instrumentação , Impressão Tridimensional/instrumentação , Biologia Sintética/instrumentação , Heme/química , Hemoglobinas/química , Humanos , Lasers , Microfluídica/métodos , Biologia Sintética/métodos , Microtomografia por Raio-X
2.
PLoS One ; 15(1): e0228140, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31978158

RESUMO

Improved capabilities in microfluidics, electrochemistry, and portable assays have resulted in the development of a wide range of point-of-use sensors intended for environmental, medical, and agricultural applications in resource-limited environments of developing countries. However, these devices are frequently developed without direct interaction with their often-remote intended user base, creating the potential for a disconnect between users' actual needs and those perceived by sensor developers. As different analytical techniques have inherent strengths and limitations, effective measurement solution development requires determination of desired sensor attributes early in the development process. In this work, we present our findings on design priorities for point-of-use microbial water sensors based on fieldwork in rural India, as well as a guide to fieldwork methodologies for determining desired sensor attributes. We utilized group design workshops for initial identification of design priorities, and then conducted choice-based conjoint analysis interviews for quantification of user preferences among these priorities. We found the highest user preference for integrated reporting of contaminant concentration and recommended actions, as well as significant preferences for mostly reusable sensor architectures, same-day results, and combined ingredients. These findings serve as a framework for future microbial sensor development and a guide for fieldwork-based understanding of user needs.


Assuntos
Água Potável/análise , Microfluídica/métodos , Qualidade da Água , Comportamento do Consumidor , Água Potável/microbiologia , Desenho de Equipamento , Empregados do Governo/psicologia , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Índia , Entrevistas como Assunto , Microfluídica/instrumentação , Sistemas Automatizados de Assistência Junto ao Leito/economia
3.
Nat Commun ; 11(1): 396, 2020 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-31959754

RESUMO

The bromeliad Tillandsia landbeckii thrives in the Atacama desert of Chile using the fog captured by specialized leaf trichomes to satisfy its water needs. However, it is still unclear how the trichome of T. landbeckii and other Tillandsia species is able to absorb fine water droplets during intermittent fog events while also preventing evaporation when the plant is exposed to the desert's hyperarid conditions. Here, we explain how a 5800-fold asymmetry in water conductance arises from a clever juxtaposition of a thick hygroscopic wall and a semipermeable membrane. While absorption is achieved by osmosis of liquid water, evaporation under dry external conditions shifts the liquid-gas interface forcing water to diffuse through the thick trichome wall in the vapor phase. We confirm this mechanism by fabricating artificial composite membranes mimicking the trichome structure. The reliance on intrinsic material properties instead of moving parts makes the trichome a promising basis for the development of microfluidics valves.


Assuntos
Materiais Biomiméticos , Microfluídica/instrumentação , Tillandsia/fisiologia , Tricomas/ultraestrutura , Água/metabolismo , Chile , Clima Desértico , Membranas Artificiais , Microfluídica/métodos , Microscopia de Fluorescência , Folhas de Planta/fisiologia , Folhas de Planta/ultraestrutura , Tillandsia/ultraestrutura , Tricomas/fisiologia
4.
Nat Biomed Eng ; 4(4): 394-406, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31988457

RESUMO

The inaccessibility of living bone marrow (BM) hampers the study of its pathophysiology under myelotoxic stress induced by drugs, radiation or genetic mutations. Here, we show that a vascularized human BM-on-a-chip (BM chip) supports the differentiation and maturation of multiple blood cell lineages over 4 weeks while improving CD34+ cell maintenance, and that it recapitulates aspects of BM injury, including myeloerythroid toxicity after clinically relevant exposures to chemotherapeutic drugs and ionizing radiation, as well as BM recovery after drug-induced myelosuppression. The chip comprises a fluidic channel filled with a fibrin gel in which CD34+ cells and BM-derived stromal cells are co-cultured, a parallel channel lined by human vascular endothelium and perfused with culture medium, and a porous membrane separating the two channels. We also show that BM chips containing cells from patients with the rare genetic disorder Shwachman-Diamond syndrome reproduced key haematopoietic defects and led to the discovery of a neutrophil maturation abnormality. As an in vitro model of haematopoietic dysfunction, the BM chip may serve as a human-specific alternative to animal testing for the study of BM pathophysiology.


Assuntos
Células da Medula Óssea/citologia , Medula Óssea/patologia , Hematopoese , Microfluídica/métodos , Animais , Antígenos CD34 , Medula Óssea/efeitos dos fármacos , Medula Óssea/efeitos da radiação , Transplante de Medula Óssea , Diferenciação Celular , Proliferação de Células , Células Cultivadas , Humanos , Dispositivos Lab-On-A-Chip , Células-Tronco Mesenquimais , Microfluídica/instrumentação
5.
Nat Biomed Eng ; 4(4): 421-436, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31988459

RESUMO

Analyses of drug pharmacokinetics (PKs) and pharmacodynamics (PDs) performed in animals are often not predictive of drug PKs and PDs in humans, and in vitro PK and PD modelling does not provide quantitative PK parameters. Here, we show that physiological PK modelling of first-pass drug absorption, metabolism and excretion in humans-using computationally scaled data from multiple fluidically linked two-channel organ chips-predicts PK parameters for orally administered nicotine (using gut, liver and kidney chips) and for intravenously injected cisplatin (using coupled bone marrow, liver and kidney chips). The chips are linked through sequential robotic liquid transfers of a common blood substitute by their endothelium-lined channels (as reported by Novak et al. in an associated Article) and share an arteriovenous fluid-mixing reservoir. We also show that predictions of cisplatin PDs match previously reported patient data. The quantitative in-vitro-to-in-vivo translation of PK and PD parameters and the prediction of drug absorption, distribution, metabolism, excretion and toxicity through fluidically coupled organ chips may improve the design of drug-administration regimens for phase-I clinical trials.


Assuntos
Dispositivos Lab-On-A-Chip , Microfluídica/métodos , Preparações Farmacêuticas , Farmacocinética , Animais , Cisplatino/farmacocinética , Desenho de Fármacos , Humanos , Técnicas In Vitro , Fígado/metabolismo , Microfluídica/instrumentação , Modelos Biológicos , Nicotina/farmacocinética , Preparações Farmacêuticas/administração & dosagem , Preparações Farmacêuticas/metabolismo
6.
Nat Protoc ; 14(12): 3366-3394, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31666743

RESUMO

Epigenetic mechanisms such as histone modifications play critical roles in adaptive tuning of chromatin structures. Profiling of various histone modifications at the genome scale using tissues from animal and human samples is an important step for functional studies of epigenomes and epigenomics-based precision medicine. Because the profile of a histone mark is highly specific to a cell type, cell isolation from tissues is often necessary to generate a homogeneous cell population, and such operations tend to yield a low number of cells. In addition, high-throughput processing is often desirable because of the multiplexity of histone marks of interest and the large quantity of samples in a hospital setting. In this protocol, we provide detailed instructions for device fabrication, setup, and operation of microfluidic oscillatory washing-based chromatin immunoprecipitation followed by sequencing (MOWChIP-seq) for profiling of histone modifications using as few as 100 cells per assay with a throughput as high as eight assays in one run. MOWChIP-seq operation involves flowing of chromatin fragments through a packed bed of antibody-coated beads, followed by vigorous microfluidic oscillatory washing. Our process is semi-automated to reduce labor and improve reproducibility. Using one eight-unit device, it takes 2 d to produce eight sequencing libraries from chromatin samples. The technology is scalable. We used the protocol to study a number of histone modifications in various types of mouse and human tissues. The protocol can be conducted by a user who is familiar with molecular biology procedures and has basic engineering skills.


Assuntos
/instrumentação , Microfluídica/instrumentação , Animais , Cromatina/genética , Imunoprecipitação da Cromatina/métodos , Epigênese Genética/genética , Epigenômica/métodos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Ensaios de Triagem em Larga Escala/instrumentação , Ensaios de Triagem em Larga Escala/métodos , Código das Histonas/genética , Código das Histonas/fisiologia , Histonas/metabolismo , Humanos , Microfluídica/métodos , Processamento de Proteína Pós-Traducional , Análise de Sequência de DNA/métodos
7.
Soft Matter ; 15(46): 9565-9578, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31724682

RESUMO

The performance of orally administered lipid-based drug formulations is crucially dependent on digestion, and understanding the colloidal structures formed during digestion is necessary for rational formulation design. Previous studies using the established bulk pH-stat approach (Hong et al. 2015), coupled to synchrotron small angle X-ray scattering (SAXS), have begun to shed light on this subject. Such studies of digestion using in situ SAXS measurements are complex and have limitations regarding the resolution of intermediate structures. Using a microfluidic device, the digestion of lipid systems may be monitored with far better control over the mixing of the components and the application of enzyme, thereby elucidating a finer understanding of the structural progression of these lipid systems. This work compares a simple T-junction microcapillary device and a custom-built microfluidic chip featuring hydrodynamic flow focusing, with an equivalent experiment with the full scale pH-stat approach. Both microfluidic devices were found to be suitable for in situ SAXS measurements in tracking the kinetics with improved time and signal sensitivity compared to other microfluidic devices studying similar lipid-based systems, and producing more consistent and controllable structural transformations. Particle sizing of the nanoparticles produced in the microfluidic devices were more consistent than the pH-stat approach.


Assuntos
Lipase/metabolismo , Lipídeos/química , Lipossomos/química , Microfluídica/métodos , Nanopartículas/química , Difração de Raios X/métodos , Composição de Medicamentos/métodos , Microfluídica/instrumentação , Espalhamento a Baixo Ângulo , Difração de Raios X/instrumentação
8.
Pharm Res ; 36(12): 183, 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31741058

RESUMO

Research conducted in microgravity conditions has the potential to yield new therapeutics, as advances can be achieved in the absence of phenomena such as sedimentation, hydrostatic pressure and thermally-induced convection. The outcomes of such studies can significantly contribute to many scientific and technological fields, including drug discovery. This article reviews the existing traditional microgravity platforms as well as emerging ideas for enabling microgravity research focusing on SpacePharma's innovative autonomous remote-controlled microgravity labs that can be launched to space aboard nanosatellites to perform drug research in orbit. The scientific literature is reviewed and examples of life science fields that have benefited from studies in microgravity conditions are given. These include the use of microgravity environment for chemical applications (protein crystallization, drug polymorphism, self-assembly of biomolecules), pharmaceutical studies (microencapsulation, drug delivery systems, behavior and stability of colloidal formulations, antibiotic drug resistance), and biological research, including accelerated models for aging, investigation of bacterial virulence , tissue engineering using organ-on-chips in space, enhanced stem cells proliferation and differentiation.


Assuntos
Simulação de Ausência de Peso/instrumentação , Simulação de Ausência de Peso/métodos , Ausência de Peso , Fatores Etários , Diferenciação Celular , Linhagem Celular , Proliferação de Células , Cristalização/instrumentação , Cristalização/métodos , Dimerização , Composição de Medicamentos/instrumentação , Composição de Medicamentos/métodos , Sistemas de Liberação de Medicamentos/instrumentação , Sistemas de Liberação de Medicamentos/métodos , Descoberta de Drogas/instrumentação , Descoberta de Drogas/métodos , Resistência Microbiana a Medicamentos , Humanos , Microfluídica/instrumentação , Microfluídica/métodos , Pesquisa Farmacêutica/instrumentação , Pesquisa Farmacêutica/métodos , Fenômenos Físicos , Proteínas/química , Voo Espacial , Engenharia Tecidual/instrumentação , Engenharia Tecidual/métodos
9.
Nature ; 574(7777): 228-232, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31597972

RESUMO

Microfluidic systems can deliver portable point-of-care diagnostics without the need for external equipment or specialist operators, by integrating all reagents and manipulations required for a particular assay in one device1. A key approach is to deposit picogram quantities of dried reagents in microchannels with micrometre precision using specialized inkjet plotters2-5. This means that reagents can be stored for long periods of time and reconstituted spontaneously when adding a liquid sample. But it is challenging to carry out complex operations using multiple reagents, because shear flow enhances their dispersion and they tend to accumulate at moving liquid fronts, resulting in poor spatiotemporal control over the concentration profile of the reconstituted reagents6. One solution is to limit the rate of release of reagents into the liquid7-10. However, this requires the fine-tuning of different reagents, conditions and targeted operations, and cannot readily produce the complex, time-dependent multireagent concentration pulses required for sophisticated on-chip assays. Here we report and characterize a capillary flow phenomenon that we term self-coalescence, which is seen when a confined liquid with a stretched air-liquid interface is forced to 'zip' back onto itself in a microfluidic channel, thereby allowing reagent reconstitution with minimal dispersion. We provide a comprehensive framework that captures the physical underpinning of this effect. We also fabricate scalable, compact and passive microfluidic structures-'self-coalescence modules', or SCMs-that exploit and control this phenomenon in order to dissolve dried reagent deposits in aqueous solutions with precise spatiotemporal control. We show that SCMs can reconstitute multiple reagents so that they either undergo local reactions or are sequentially delivered in a flow of liquid. SCMs are easily fabricated in different materials, readily configured to enable different reagent manipulations, and readily combined with other microfluidic technologies, so should prove useful for assays, diagnostics, high-throughput screening and other technologies requiring efficient preparation and manipulation of small volumes of complex solutions.


Assuntos
Indicadores e Reagentes/análise , Microfluídica/métodos , Técnicas de Química Analítica/instrumentação , Técnicas de Química Analítica/métodos , Testes Diagnósticos de Rotina , Ensaios Enzimáticos/instrumentação , Ensaios Enzimáticos/métodos , Fluorometria , Glucosefosfato Desidrogenase/análise , Glucosefosfato Desidrogenase/metabolismo , Papillomavirus Humano 16/genética , Papillomavirus Humano 16/isolamento & purificação , Papillomavirus Humano 18/genética , Papillomavirus Humano 18/isolamento & purificação , Humanos , Microfluídica/instrumentação , Técnicas de Amplificação de Ácido Nucleico/instrumentação , Técnicas de Amplificação de Ácido Nucleico/métodos
10.
Adv Exp Med Biol ; 1146: 79-103, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31612455

RESUMO

The last 20 years have seen the blooming of microfluidics technologies applied to biological sciences. Microfluidics provides effective tools for biological analysis, allowing the experimentalists to extend their playground to single cells and single molecules, with high throughput and resolution which were inconceivable few decades ago. In particular, microfluidic devices are profoundly changing the conventional way of studying the cell motility and cell migratory dynamics. In this chapter we will furnish a comprehensive view of the advancements made in the research domain of confinement-induced cell migration, thanks to the use of microfluidic devices. The chapter is subdivided in three parts. Each section will be addressing one of the fundamental questions that the microfluidic technology is contributing to unravel: (i) where cell migration takes place, (ii) why cells migrate and, (iii) how the cells migrate. The first introductory part is devoted to a thumbnail, and partially historical, description of microfluidics and its impact in biological sciences. Stress will be put on two aspects of the devices fabrication process, which are crucial for biological applications: materials used and coating methods. The second paragraph concerns the cell migration induced by environmental cues: chemical, leading to chemotaxis, mechanical, at the basis of mechanotaxis, and electrical, which induces electrotaxis. Each of them will be addressed separately, highlighting the fundamental role of microfluidics in providing the well-controlled experimental conditions where cell migration can be induced, investigated and ultimately understood. The third part of the chapter is entirely dedicated to how the cells move in confined environments. Invadosomes (the joint name for podosomes and invadopodia) are cell protrusion that contribute actively to cell migration or invasion. The formation of invadosomes under confinement is a research topic that only recently has caught the attention of the scientific community: microfluidic design is helping shaping the future direction of this emerging field of research.


Assuntos
Movimento Celular , Microfluídica , Podossomos , Animais , Quimiotaxia , Humanos , Dispositivos Lab-On-A-Chip , Microfluídica/instrumentação , Podossomos/metabolismo , Pesquisa/tendências
11.
Anal Chim Acta ; 1089: 108-114, 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-31627807

RESUMO

Droplet microfluidics has the ability to greatly increase the throughput of screening and sorting of enzymes by carrying reagents in picoliter droplets flowing in inert oils. It was found with the use of a specific surfactant, the interfacial tension of droplets can be very sensitive to droplet pH. This enables the sorting of droplets of different pH when confined droplets encounter a microfabricated trench. The device can be extended to sort enzymes, as a large number of enzymatic reactions lead to the production of an acidic or basic product and a concurrent change in solution pH. The progress of an enzymatic reaction is tracked from the position of a flowing train of droplets. We demonstrate the sorting of esterase isoenzymes based on their enzymatic activity. This label-free technology, that we dub droplet sorting by interfacial tension (SIFT), requires no active components and would have applications for enzyme sorting in high-throughput applications that include enzyme screening and directed evolution of enzymes.


Assuntos
Hidrolases de Éster Carboxílico/isolamento & purificação , Ensaios Enzimáticos/métodos , Acetatos/química , Animais , Hidrolases de Éster Carboxílico/química , Ensaios Enzimáticos/instrumentação , Fluorcarbonetos/química , Isoenzimas/química , Isoenzimas/isolamento & purificação , Dispositivos Lab-On-A-Chip , Fígado/enzimologia , Microfluídica/instrumentação , Microfluídica/métodos , Óleos/química , Fenóis/química , Reprodutibilidade dos Testes , Tensão Superficial , Suínos , Água/química
12.
Molecules ; 24(18)2019 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-31547232

RESUMO

Use of sonication for designing and fabricating reactors, especially the deposition of catalysts inside a microreactor, is a modern approach. There are many reports that prove that a microreactor is a better setup compared with batch reactors for carrying out catalytic reactions. Microreactors have better energy efficiency, reaction rate, safety, a much finer degree of process control, better molecular diffusion, and heat-transfer properties compared with the conventional batch reactor. The use of microreactors for photocatalytic reactions is also being considered to be the appropriate reactor configuration because of its improved irradiation profile, better light penetration through the entire reactor depth, and higher spatial illumination homogeneity. Ultrasound has been used efficiently for the synthesis of materials, degradation of organic compounds, and fuel production, among other applications. The recent increase in energy demands, as well as the stringent environmental stress due to pollution, have resulted in the need to develop green chemistry-based processes to generate and remove contaminants in a more environmentally friendly and cost-effective manner. It is possible to carry out the synthesis and deposition of catalysts inside the reactor using the ultrasound-promoted method in the microfluidic system. In addition, the synergistic effect generated by photocatalysis and sonochemistry in a microreactor can be used for the production of different chemicals, which have high value in the pharmaceutical and chemical industries. The current review highlights the use of both photocatalysis and sonochemistry for developing microreactors and their applications.


Assuntos
Fotoquímica/instrumentação , Sonicação/métodos , Catálise , Desenho de Equipamento , Microfluídica/instrumentação , Nanopartículas/química , Fotoquímica/métodos , Ultrassom/instrumentação , Ultrassom/métodos
13.
Nat Protoc ; 14(11): 3144-3161, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31554957

RESUMO

The analysis of bacteria at the single-cell level is essential to characterization of processes in which cellular heterogeneity plays an important role. BACMMAN (bacteria mother machine analysis) is a software allowing fast and reliable automated image analysis of high-throughput 2D or 3D time-series images from experiments using the 'mother machine', a very popular microfluidic device allowing biological processes in bacteria to be investigated at the single-cell level. Here, we describe how to use some of the BACMMAN features, including (i) segmentation and tracking of bacteria and intracellular fluorescent spots, (ii) visualization and editing of the results, (iii) configuration of the image-processing pipeline for different datasets and (iv) BACMMAN coupling to data analysis software for visualization and analysis of data subsets with specific properties. Among software specifically dedicated to the analysis of mother machine data, only BACMMAN allows segmentation and tracking of both bacteria and intracellular spots. For a single position, single channel with 1,000 frames (2-GB dataset), image processing takes ~6 min on a regular computer. Numerous implemented algorithms, easy configuration and high modularity ensure wide applicability of the BACMMAN software.


Assuntos
Escherichia coli/crescimento & desenvolvimento , Processamento de Imagem Assistida por Computador/métodos , Microfluídica/métodos , Análise de Célula Única/métodos , Software , Imagem com Lapso de Tempo/métodos , Evolução Biológica , Escherichia coli/genética , Microfluídica/instrumentação , Microscopia de Fluorescência/métodos , Mutação
14.
Int J Mol Sci ; 20(18)2019 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-31533368

RESUMO

Diseases caused by multi-drug resistant pathogens have become a global concern. Therefore, new approaches suitable for treating these bacteria are urgently needed. In this study, we analyzed genetically encoded photosensitizers (PS) related to the green fluorescent protein (GFP) or light-oxygen-voltage (LOV) photoreceptors for their exogenous applicability as light-triggered antimicrobial agents. Depending on their specific photophysical properties and photochemistry, these PSs can produce different toxic ROS (reactive oxygen species) such as O2•- and H2O2 via type-I, as well as 1O2 via type-II reaction in response to light. By using cell viability assays and microfluidics, we could demonstrate differences in the intracellular and extracellular phototoxicity of the applied PS. While intracellular expression and exogenous supply of GFP-related PSs resulted in a slow inactivation of E. coli and pathogenic Gram-negative and Gram-positive bacteria, illumination of LOV-based PSs such as the singlet oxygen photosensitizing protein SOPP3 resulted in a fast and homogeneous killing of these microbes. Furthermore, our data indicate that the ROS type and yield as well as the localization of the applied PS protein can strongly influence the antibacterial spectrum and efficacy. These findings open up new opportunities for photodynamic inactivation of pathogenic bacteria.


Assuntos
Anti-Infecciosos/farmacologia , Luz , Fármacos Fotossensibilizantes/farmacologia , Proteínas Recombinantes/farmacologia , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Bactérias/metabolismo , Biomarcadores , Relação Dose-Resposta a Droga , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Escherichia coli/metabolismo , Genes Reporter , Microfluídica/instrumentação , Microfluídica/métodos
15.
ACS Appl Mater Interfaces ; 11(40): 37313-37321, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31517474

RESUMO

A simple process is developed for the one-step preparation of dual-compartment alginate microcapsules with controlled size and structure from microfluid-generated water-in-water-in-oil (W/W/O) emulsion droplet. Unlike other methods that rely on transient W/W/O emulsion droplet, we introduce an aqueous two-phase system (ATPS) to form a stable W/W/O emulsion droplet as a template for preparing dual-compartment alginate microcapsules. Two different bioactive molecules are able to be spatially confined encapsulated in the shell and core of alginate microcapsules due to the partitioning effect of ATPS and the high viscosity of alginate solution. Moreover, an enzyme cascade reaction with a spatial confined glucose oxidase and horseradish peroxidase in the shell and core of alginate microcapsules confirms its excellent biocompatibility and high activity. This method provides a green platform for enzyme-catalyzed tandem reactions and controlled sequential release of multiple drugs based on alginate microcapsules.


Assuntos
Alginatos/química , Cápsulas/química , Emulsões/química , Microfluídica , Óleos/química , Água/química , Biocatálise , Fluoresceína-5-Isotiocianato/análogos & derivados , Glucose Oxidase/metabolismo , Peroxidase do Rábano Silvestre/metabolismo , Microfluídica/instrumentação , Tamanho da Partícula , Soroalbumina Bovina
16.
Sensors (Basel) ; 19(15)2019 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-31382441

RESUMO

In this paper, we demonstrate the possibility of direct protein sensing beyond the Debye length limit using a molecular-charge-contact (MCC)-based ion-sensitive field-effect transistor (ISFET) sensor combined with a microfluidic device. Different from the MCC method previously reported, biotin-coated magnetic beads are set on the gate insulator of an ISFET using a button magnet before the injection of target molecules such as streptavidin. Then, the streptavidin-a biotin interaction, used as a model of antigen-antibody reaction is expected at the magnetic beads/gate insulator nanogap interface, changing the pH at the solution/dielectric interface owing to the weak acidity of streptavidin. In addition, the effect of the pH or ionic strength of the measurement solutions on the electrical signals of the MCC-based ISFET sensor is investigated. Furthermore, bound/free (B/F) molecule separation with a microfluidic device is very important to obtain an actual electrical signal based on the streptavidin-biotin interaction. Platforms based on the MCC method are suitable for exploiting the advantages of ISFETs as pH sensors, that is, direct monitoring systems for antigen-antibody reactions in the field of in vitro diagnostics.


Assuntos
Microfluídica/métodos , Proteínas/análise , Transistores Eletrônicos , Reações Antígeno-Anticorpo , Biotina/química , Biotina/metabolismo , Concentração de Íons de Hidrogênio , Íons/química , Limite de Detecção , Microfluídica/instrumentação , Concentração Osmolar , Estreptavidina/química , Estreptavidina/metabolismo
17.
Nat Commun ; 10(1): 3544, 2019 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-31391463

RESUMO

Simultaneous measurement of proteins and mRNA in single cells enables quantitative understanding and modeling of cellular functions. Here, we present an automated microfluidic system for multi-parameter and ultra-sensitive protein/mRNA measurements in single cells. Our technology improves the sensitivity of digital proximity ligation assay by up to 55-fold, with a detection limit of 2277 proteins per cell and with detection efficiency of as few as 29 protein molecules. Our measurements using this system reveal higher mRNA/protein correlation in single mammalian cells than previous estimates. Furthermore, time-lapse imaging of herpes simplex virus 1 infected epithelial cells enabled by our device shows that expression of ICP4 -a major transcription factor regulating hundreds of viral genes- is only partially correlated with viral protein counts, suggesting that many cells go through abortive infection. These results highlight the importance of high-sensitivity protein/mRNA quantification for understanding fundamental molecular mechanisms in individual cells.


Assuntos
Proteínas/isolamento & purificação , RNA Mensageiro/isolamento & purificação , Análise de Célula Única/métodos , Animais , Dosagem de Genes , Humanos , Microscopia Intravital/instrumentação , Microscopia Intravital/métodos , Dispositivos Lab-On-A-Chip , Limite de Detecção , Microfluídica/instrumentação , Microfluídica/métodos , Análise de Célula Única/instrumentação , Imagem com Lapso de Tempo/instrumentação , Imagem com Lapso de Tempo/métodos , Células Vero
18.
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
19.
Molecules ; 24(16)2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31394856

RESUMO

Paper-based microfluidic devices have advanced significantly in recent years as they are affordable, automated with capillary action, portable, and biodegradable diagnostic platforms for a variety of health, environmental, and food quality applications. In terms of commercialization, however, paper-based microfluidics still have to overcome significant challenges to become an authentic point-of-care testing format with the advanced capabilities of analyte purification, multiplex analysis, quantification, and detection with high sensitivity and selectivity. Moreover, fluid flow manipulation for multistep integration, which involves valving and flow velocity control, is also a critical parameter to achieve high-performance devices. Considering these limitations, the aim of this review is to (i) comprehensively analyze the fabrication techniques of microfluidic paper-based analytical devices, (ii) provide a theoretical background and various methods for fluid flow manipulation, and iii) highlight the recent detection techniques developed for various applications, including their advantages and disadvantages.


Assuntos
Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas , Microfluídica/instrumentação , Microfluídica/métodos , Algoritmos , Desenho de Equipamento , Humanos , Modelos Teóricos , Papel
20.
Int J Nanomedicine ; 14: 4187-4209, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31289440

RESUMO

Circulating tumor cells (CTCs) are disseminated cancer cells. The occurrence and circulation of CTCs seem key for metastasis, still the major cause of cancer-associated deaths. As such, CTCs are investigated as predictive biomarkers. However, due to their rarity and heterogeneous biology, CTCs' practical use has not made it into the clinical routine. Clearly, methods for the effective isolation and reliable detection of CTCs are urgently needed. With the development of nanotechnology, various nanosystems for CTC isolation and enrichment and CTC-targeted cancer therapy have been designed. Here, we summarize the relationship between CTCs and tumor metastasis, and describe CTCs' unique properties hampering their effective enrichment. We comment on nanotechnology-based systems for CTC isolation and recent achievements in microfluidics and lab-on-a-chip technologies. We discuss recent advances in CTC-targeted cancer therapy exploiting the unique properties of nanomaterials. We conclude by introducing developments in CTC-directed nanosystems and other advanced technologies currently in (pre)clinical research.


Assuntos
Biomarcadores Tumorais/análise , Separação Celular/métodos , Nanomedicina/métodos , Células Neoplásicas Circulantes/patologia , Biomarcadores Tumorais/isolamento & purificação , Materiais Biomiméticos , Grafite , Humanos , Dispositivos Lab-On-A-Chip , Microfluídica/instrumentação , Microfluídica/métodos , Nanoestruturas/química , Nanotecnologia/métodos , Nanotubos de Carbono
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA