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1.
J Cell Sci ; 135(5)2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33414166

RESUMO

Ferroptosis is a regulated, non-apoptotic form of cell death, characterized by hydroxy-peroxidation of discrete phospholipid hydroperoxides, particularly hydroperoxyl (Hp) forms of arachidonoyl- and adrenoyl-phosphatidylethanolamine, with a downstream cascade of oxidative damage to membrane lipids, proteins and DNA, culminating in cell death. We recently showed that human trophoblasts are particularly sensitive to ferroptosis caused by depletion or inhibition of glutathione peroxidase 4 (GPX4) or the lipase PLA2G6. Here, we show that trophoblastic ferroptosis is accompanied by a dramatic change in the trophoblast plasma membrane, with macro-blebbing and vesiculation. Immunofluorescence revealed that ferroptotic cell-derived blebs stained positive for F-actin, but negative for cytoplasmic organelle markers. Transfer of conditioned medium that contained detached macrovesicles or co-culture of wild-type target cells with blebbing cells did not stimulate ferroptosis in target cells. Molecular modeling showed that the presence of Hp-phosphatidylethanolamine in the cell membrane promoted its cell ability to be stretched. Together, our data establish that membrane macro-blebbing is characteristic of trophoblast ferroptosis and can serve as a useful marker of this process. Whether or not these blebs are physiologically functional remains to be established.

2.
Sci Adv ; 5(8): eaax0729, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31467978

RESUMO

Cell-cell communication plays a pivotal role in coordination and function of biological systems. Three-dimensional (3D) spheroids provide venues to explore cellular communication for tissue development and drug discovery, as their 3D architecture mimics native in vivo microenvironments. Cellular electrophysiology is a prevalent signaling paradigm for studying electroactive cells. Currently, electrophysiological studies do not provide direct, multisite, simultaneous investigation of tissues in 3D. In this study, 3D self-rolled biosensor arrays (3D-SR-BAs) of either active field-effect transistors or passive microelectrodes were implemented to interface human cardiac spheroids in 3D. The arrays provided continuous and stable multiplexed recordings of field potentials with high sensitivity and spatiotemporal resolution, supported with simultaneous calcium imaging. Our approach enables electrophysiological investigation and monitoring of the complex signal transduction in 3D cellular assemblies toward an organ-on-an-electronic-chip (organ-on-e-chip) platform for tissue maturation investigations and development of drugs for disease treatment, such as arrhythmias.


Assuntos
Técnicas Biossensoriais/métodos , Comunicação Celular , Microeletrodos , Esferoides Celulares/fisiologia , Humanos
3.
Proc Natl Acad Sci U S A ; 115(49): 12359-12364, 2018 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-30455311

RESUMO

Morphogenesis is a phenomenon by which a wide variety of functional organs are formed in biological systems. In plants, morphogenesis is primarily driven by differential growth of tissues. Much effort has been devoted to identifying the role of genetic and biomolecular pathways in regulating cell division and cell expansion and in influencing shape formation in plant organs. However, general principles dictating how differential growth controls the formation of complex 3D shapes in plant leaves and flower petals remain largely unknown. Through quantitative measurements on live plant organs and detailed finite-element simulations, we show how the morphology of a growing leaf is determined by both the maximum value and the spatial distribution of growth strain. With this understanding, we develop a broad scientific framework for a morphological phase diagram that is capable of rationalizing four configurations commonly found in plant organs: twisting, helical twisting, saddle bending, and edge waving. We demonstrate the robustness of these findings and analyses by recourse to synthetic reproduction of all four configurations using controlled polymerization of a hydrogel. Our study points to potential approaches to innovative geometrical design and actuation in such applications as building architecture, soft robotics and flexible electronics.


Assuntos
Flores/crescimento & desenvolvimento , Orchidaceae/crescimento & desenvolvimento , Desenvolvimento Vegetal , Folhas de Planta/crescimento & desenvolvimento , Modelos Biológicos
4.
Adv Mater ; 30(31): e1801669, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29921009

RESUMO

Self-folding microgrippers are an emerging class of smart structures that have widespread applications in medicine and micro/nanomanipulation. To achieve their functionalities, these architectures rely on spatially patterned hinges to transform into 3D configurations in response to an external stimulus. Incorporating hinges into the devices requires the processing of multiple layers which eventually increases the fabrication costs and actuation complexities. The goal of this work is to demonstrate that it is possible to achieve gripper-like configurations in an on-demand manner from simple planar bilayers that do not require hinges for their actuation. Finite element modeling of bilayers is performed to understand the mechanics behind their stimuli-responsive shape transformation behavior. The model predictions are then experimentally validated and axisymmetric gripper-like shapes are realized using millimeter-scale poly(dimethylsiloxane) bilayers that undergo differential swelling in organic solvents. Owing to the nature of the computational scheme which is independent of length scales and material properties, the guidelines reported here would be applicable to a diverse array of gripping systems and functional devices. Thus, this work not only demonstrates a simple route to fabricate functional microgrippers but also contributes to self-assembly in general.


Assuntos
Análise de Elementos Finitos , Dimetilpolisiloxanos/química , Compostos Orgânicos/química , Robótica , Solventes/química
5.
Proc Natl Acad Sci U S A ; 115(1): 70-74, 2018 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-29255037

RESUMO

Many applications in tissue engineering, flexible electronics, and soft robotics call for approaches that are capable of producing complex 3D architectures in soft materials. Here we present a method using molecular self-assembly to generate hydrogel-based 3D architectures that resembles the appealing features of the bottom-up process in morphogenesis of living tissues. Our strategy effectively utilizes the three essential components dictating living tissue morphogenesis to produce complex 3D architectures: modulation of local chemistry, material transport, and mechanics, which can be engineered by controlling the local distribution of polymerization inhibitor (i.e., oxygen), diffusion of monomers/cross-linkers through the porous structures of cross-linked polymer network, and mechanical constraints, respectively. We show that oxygen plays a role in hydrogel polymerization which is mechanistically similar to the role of growth factors in tissue growth, and the continued growth of hydrogel enabled by diffusion of monomers/cross-linkers into the porous hydrogel similar to the mechanisms of tissue growth enabled by material transport. The capability and versatility of our strategy are demonstrated through biomimetics of tissue morphogenesis for both plants and animals, and its application to generate other complex 3D architectures. Our technique opens avenues to studying many growth phenomena found in nature and generating complex 3D structures to benefit diverse applications.


Assuntos
Materiais Biomiméticos , Hidrogéis , Engenharia Tecidual , Tecidos Suporte/química , Materiais Biomiméticos/síntese química , Materiais Biomiméticos/química , Humanos , Hidrogéis/síntese química , Hidrogéis/química , Porosidade
6.
Proc Natl Acad Sci U S A ; 114(11): 2910-2915, 2017 03 14.
Artigo em Inglês | MEDLINE | ID: mdl-28265065

RESUMO

When detergents and phospholipid membranes are dispersed in aqueous solutions, they tend to self-assemble into vesicles of various shapes and sizes by virtue of their hydrophobic and hydrophilic segments. A clearer understanding of such vesiculation processes holds promise for better elucidation of human physiology and disease, and paves the way to improved diagnostics, drug development, and drug delivery. Here we present a detailed analysis of the energetics and thermodynamics of vesiculation by recourse to nonlinear elasticity, taking into account large deformation that may arise during the vesiculation process. The effects of membrane size, spontaneous curvature, and membrane stiffness on vesiculation and vesicle size distribution were investigated, and the critical size for vesicle formation was determined and found to compare favorably with available experimental evidence. Our analysis also showed that the critical membrane size for spontaneous vesiculation was correlated with membrane thickness, and further illustrated how the combined effects of membrane thickness and physical properties influenced the size, shape, and distribution of vesicles. These findings shed light on the formation of physiological extracellular vesicles, such as exosomes. The findings also suggest pathways for manipulating the size, shape, distribution, and physical properties of synthetic vesicles, with potential applications in vesicle physiology, the pathobiology of cancer and other diseases, diagnostics using in vivo liquid biopsy, and drug delivery methods.


Assuntos
Fosfolipídeos/química , Lipossomas Unilamelares/química , Exossomos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Bicamadas Lipídicas/química , Modelos Biológicos , Tamanho da Partícula
7.
Soft Matter ; 12(29): 6184-95, 2016 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-27435451

RESUMO

We investigate mismatch strain driven programmable shape transformation of spherical domes and report the effects of different geometric and structural characteristics on dome behavior in response to applied mismatch strain. We envision a bilayer dome design where the differential swelling of the inner layer with respect to the passive outer layer in response to changes in dome surroundings (such as the introduction of an organic solvent) introduces mismatch strain within the bilayer system and causes dome shape transformation. Finite element analysis reveals that, in addition to snap-through, spherical domes undergo bifurcation buckling and eventually gradual bending to morph into cylinders with increasing mismatch strain. Besides demonstrating how the snap-through energy barrier depends on the spherical dome shape, our analysis identifies three distinct groups of dome geometries based on their mismatch strain-transformed configuration relationships. Our experiments with polymer-based elastic bilayer domes that exhibit differential swelling in organic solvents qualitatively confirm the finite element predictions. We establish that, in addition to externally applied stimuli (mismatch strain), bilayer spherical dome morphing can be tuned and hence programmed through its geometry and structural characteristics. Incorporation of an elastic instability mechanism such as snap-through within the framework of stimuli-responsive functional devices can improve their response time which is otherwise controlled by diffusion. Hence, our proposed design guidelines can be used to realize deployable, multi-functional, reconfigurable, and therefore, adaptive structures responsive to a diverse set of stimuli across multiple length scales.

8.
Biotechnol Bioeng ; 113(11): 2496-506, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27183296

RESUMO

Durotaxis, a phenomenon that cells move according to changes in stiffness of the extra cellular matrix, has emerged as a crucial parameter controlling cell migration behavior. The current study provides a simple method to generate three-dimensional continuous stiffness variations without changing other physical characteristics of the extra cellular environment. Using Finite Element simulations, the stiffness and the stiffness gradient variations are evaluated quantitatively, leading to an analysis of the dependence of cell migration behavior on the substrate stiffness parameters. We tested various cell lines on several 3-D environments. The durotaxis results show that the cell migration velocity does not have any consistency with the stiffness of the substrate, rather it is more related to the stiffness gradient of the substrate. This finding suggests a new mechanism underlying the durotaxis phenomenon, highlighting the importance of the substrate stiffness gradient, rather than the stiffness itself. Biotechnol. Bioeng. 2016;113: 2496-2506. © 2016 Wiley Periodicals, Inc.


Assuntos
Técnicas de Cultura Celular por Lotes/métodos , Movimento Celular/fisiologia , Mecanotransdução Celular/fisiologia , Modelos Biológicos , Resposta Táctica/fisiologia , Engenharia Tecidual/métodos , Adulto , Animais , Células Cultivadas , Simulação por Computador , Módulo de Elasticidade/fisiologia , Feminino , Humanos , Camundongos , Camundongos Endogâmicos C3H , Estresse Mecânico
9.
Small ; 11(45): 6051-7, 2015 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-26449185

RESUMO

The fabrication and properties of pH-responsive colloidal particles are reported, which change shape rapidly (less than 200 ms), nearly independent of the diffusion of the pH altering species that trigger their actuation, and far more rapid than their Brownian motion. These particles are mechanically bistable, as revealed by their hysteretic shape response. Finite element analysis (FEA) shows that mechanical hysteresis and bistability derives from the colloids' spherical curvature. Mechanical characterization of the bilayered polymers comprising the colloidal particles shows that viscoelastic relaxation plays a non-negligible role in limiting the shape switching rate; however, energy landscapes obtained from FEA simulations suggest that by tuning the elastic moduli and thicknesses of the constituent polymer layers, microparticles of the size shown here may be fabricated to actuate on timescales as fast as 1 µs.

10.
ACS Nano ; 9(2): 1985-94, 2015 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-25639798

RESUMO

Stability and high energy densities are essential qualities for emerging battery electrodes. Because of its high specific capacity, silicon has been considered a promising anode candidate. However, the several-fold volume changes during lithiation and delithiation leads to fractures and continuous formation of an unstable solid-electrolyte interphase (SEI) layer, resulting in rapid capacity decay. Here, we present a carbon-silicon-carbon (C@Si@C) nanotube sandwich structure that addresses the mechanical and chemical stability issues commonly associated with Si anodes. The C@Si@C nanotube array exhibits a capacity of ∼2200 mAh g(-1) (∼750 mAh cm(-3)), which significantly exceeds that of a commercial graphite anode, and a nearly constant Coulombic efficiency of ∼98% over 60 cycles. In addition, the C@Si@C nanotube array gives much better capacity and structure stability compared to the Si nanotubes without carbon coatings, the ZnO@C@Si@C nanorods, a Si thin film on Ni foam, and C@Si and Si@C nanotubes. In situ SEM during cycling shows that the tubes expand both inward and outward upon lithiation, as well as elongate, and then revert back to their initial size and shape after delithiation, suggesting stability during volume changes. The mechanical modeling indicates the overall plastic strain in a nanotube is much less than in a nanorod, which may significantly reduce low-cycle fatigue. The sandwich-structured nanotube design is quite general, and may serve as a guide for many emerging anode and cathode systems.

11.
Nano Lett ; 14(11): 6293-7, 2014 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-25300010

RESUMO

Micro- and nanoscale tubular structures can be formed by strain-induced self-rolled-up nanomembranes. Precision engineering of the shape and dimension determines the performance of devices based on this platform for electronic, optical, and biological applications. A transient quasi-static finite element method (FEM) with moving boundary conditions is proposed as a general approach to design diverse types of three-dimensional (3D) rolled-up geometries. This method captures the dynamic release process of membranes through etching driven by mismatch strain and accurately predicts the final dimensions of rolled-up structures. Guided by the FEM modeling, experimental demonstration using silicon nitride membranes was achieved with unprecedented precision including controlling fractional turns of a rolled-up membrane, anisotropic rolling to form helical structures, and local stress control for 3D hierarchical architectures.

12.
Biotechnol Bioeng ; 111(8): 1617-26, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24643546

RESUMO

In this study, we investigate the effects of micron-scale surface patterns on the alignment of individual cells and groups of cells. Using a simple replication molding process we produce a number of micron-scale periodic wavy patterns with different pitch and depth. We observe C2C12 cells as they grow to confluence on these patterns and find that, for some geometries, cell-cell interaction leads to global alignment in a confluent culture when individual cells would not align on the same pattern. Three types of alignment behavior are thus defined: no alignment, immediate alignment, and alignment upon confluence. To further characterize this response, we introduce a non-dimensional parameter that describes the aligning power of a periodic pattern based on its geometry. The three types of alignment behavior can be distinguished by the value of the alignment parameter, and we identify values at which the transitions in alignment behavior occur. Applying this parameter to data from the current and several earlier studies reveals that the parameter successfully describes substrate aligning power over a wide range of length scales for both wavy and grooved features.


Assuntos
Mioblastos/citologia , Nanoestruturas/ultraestrutura , Tecidos Suporte/química , Animais , Comunicação Celular , Linhagem Celular , Camundongos , Fibras Musculares Esqueléticas/citologia , Nanoestruturas/química , Propriedades de Superfície
13.
Biosens Bioelectron ; 43: 186-92, 2013 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-23306074

RESUMO

Taste receptor cells in taste buds can generate action potentials in response to taste stimuli. The spatiotemporal patterns of the potentials have great value in both biomedical and engineering researches. In the present study, by fixing the biological epithelium onto the surface of microelectrode arrays (MEA), we established a novel taste sensor to record action potentials from the taste receptor cells of rat in response to taste stimuli. By this multi-channel recording method, we examined the electrophysiological activities of taste receptor cells in taste buds to stimuli representing the basic taste qualities (sour, salt, bitter, sweet and umami). The recorded action potentials corresponding to five tastes displayed different spatiotemporal patterns. The multi-channel results demonstrated that taste buds released the spontaneous signals simultaneously and displayed different responses to different tastes stimulations. The temporal characteristics were derived by time-domain and frequency-domain analysis, and the signals fired in different stimuli could be distinguished into different clusters by principal component analysis (PCA). The study provides an effective and reliable platform to recognize and distinguish basic taste qualities.


Assuntos
Potenciais de Ação/fisiologia , Bioensaio/instrumentação , Biomimética/instrumentação , Técnicas Biossensoriais/instrumentação , Microeletrodos , Papilas Gustativas/fisiologia , Paladar/fisiologia , Animais , Desenho de Equipamento , Análise de Falha de Equipamento , Ratos , Ratos Sprague-Dawley
14.
Biosens Bioelectron ; 40(1): 174-9, 2013 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-22902534

RESUMO

By mimicking biological olfaction, biosensors have been used for the detection of important ligands in complex environments. An olfactory biosensor based on chemosensory proteins (CSPs) was designed by immobilizing honeybee CSPs (Ac-ASP3) on the interdigitated golden electrodes. Its responses to ligands of pheromones and floral odors were recorded by impedance spectroscopy. The relative decrease of charge transfer resistance of the biosensor is proportional to the logarithm of ligand concentration from 10(-7)M to 10(-3)M. To explore the molecular recognition processes of the biosensor, the tertiary structure of the protein was modeled and the protein-ligand interactions were investigated by the molecular docking. Our docking results verified the validity of experiments and showed that the specific ligands could form hydrogen bonds with some of the conserved residues, such as Cys 60 and Gln 64 of Ac-ASP3. Furthermore, combining the molecular modeling with impedance detection, the accuracy, specificity and predictability of the ligands binding to the protein could be improved. Thus, CSPs will provide a promising approach for chemical molecular sensing at low concentrations.


Assuntos
Abelhas/fisiologia , Materiais Biomiméticos , Espectroscopia Dielétrica/instrumentação , Proteínas de Insetos/química , Odorantes/análise , Feromônios/análise , Olfato/fisiologia , Animais , Simulação por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Modelos Químicos , Simulação de Acoplamento Molecular , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
15.
Biosens Bioelectron ; 40(1): 115-20, 2013 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-22883749

RESUMO

Taste has received great attention for its potential applications. In this work, we combine the biological tissue with micro-chips to establish a novel bioelectronic tongue system for salt taste detection. Before experiment, we established a computational model of action potential in salt taste receptor cell, simulating the responsive results to natural salt stimuli of NaCl solution with various concentrations. Then 36-channel microelectrode arrays (MEA) with the diameter of 30 µm were fabricated on the glass substrate, and taste epithelium was stripped from rat and fixed on MEA. When stimulated by the salt stimuli, electrophysiological activities of taste receptor cells in taste buds were measured through a multi-channel recording system. Both simulation and experiment results showed a dose-dependent increase in NaCl-induced potentials of taste receptor cells, which indicated good applications in salt measurements. The multi-channel analysis demonstrated that different groups of MEA channels were activated during stimulations, indicating non-overlapping populations of receptor cells in taste buds involved in salt taste perception. The study provides an effective and reliable biosensor platform to help recognize and distinguish salt taste components.


Assuntos
Órgãos Bioartificiais , Bioensaio/instrumentação , Microeletrodos , Cloreto de Sódio/análise , Cloreto de Sódio/farmacologia , Papilas Gustativas/fisiologia , Paladar/fisiologia , Animais , Materiais Biomiméticos , Técnicas Biossensoriais/instrumentação , Condutometria/instrumentação , Eletrônica/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Humanos , Técnicas In Vitro , Ratos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Paladar/efeitos dos fármacos , Papilas Gustativas/efeitos dos fármacos
16.
Biomed Microdevices ; 14(6): 1055-61, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23053447

RESUMO

Bio-hybrid systems provide an opportunity for integrating a living bio-active unit and a proper biosensing system, to employ the unique properties of the bio-active unit. The biological olfactory system can sense and identify thousands of trace odors. The purpose of this study is to combine olfactory epithelium with microelectrode array (MEA) to establish an olfactory epithelium-MEA hybrid system to record the odor-induced electrophysiological activities of the tissue. In our experiments, extracellular potential of olfactory receptor neurons in intact epithelium were measured in the presence of ethyl ether, acetic acid, butanedione, and acetone, respectively. After the odor-induced response signals were analyzed in the time and frequency domain, the temporal characteristics of response signals were extracted. We found that olfactory epithelium-MEA hybrid system can reflect the in vitro odor information of different signal characteristics and firing modes in vitro. The bio-hybrid sensing system can represent a useful instrument to sense and detect the odorant molecules with well recognizing patterns. With the development of sensor technology, bio-hybrid systems will represent emerging and promising platforms for wide applications, ranging from health care to environmental monitoring.


Assuntos
Técnicas Biossensoriais/instrumentação , Quimera/metabolismo , Odorantes/análise , Mucosa Olfatória/fisiologia , Neurônios Receptores Olfatórios/fisiologia , Animais , Técnicas Biossensoriais/métodos , Fenômenos Eletrofisiológicos/fisiologia , Microeletrodos , Neurônios/citologia , Neurônios/fisiologia , Percepção Olfatória/fisiologia , Ratos , Ratos Sprague-Dawley
18.
J Vis Exp ; (48)2011 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-21339720

RESUMO

Microfluidic devices have advanced cell studies by providing a dynamic fluidic environment on the scale of the cell for studying, manipulating, sorting and counting cells. However, manipulating the cell within the fluidic domain remains a challenge and requires complicated fabrication protocols for forming valves and electrodes, or demands specialty equipment like optical tweezers. Here, we demonstrate that conventional printed circuit boards (PCB) can be used for the non-contact manipulation of cells by employing dielectrophoresis (DEP) for bead and cell manipulation in laminar flow fields for bioactuation, and for cell and bead separation in multichannel microfluidic devices. First, we present the protocol for assembling the DEP electrodes and microfluidic devices, and preparing the cells for DEP. Then, we characterize the DEP operation with polystyrene beads. Lastly, we show representative results of bead and cell separation in a multichannel microfluidic device. In summary, DEP is an effective method for manipulating particles (beads or cells) within microfluidic devices.


Assuntos
Eletroforese/instrumentação , Eletroforese/métodos , Técnicas Analíticas Microfluídicas/instrumentação , Técnicas Analíticas Microfluídicas/métodos , Eletrodos , Ambiente Controlado
19.
Proc Natl Acad Sci U S A ; 107(48): 20691-6, 2010 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-21068372

RESUMO

The characterization of physical properties of cells such as their mass and stiffness has been of great interest and can have profound implications in cell biology, tissue engineering, cancer, and disease research. For example, the direct dependence of cell growth rate on cell mass for individual adherent human cells can elucidate the mechanisms underlying cell cycle progression. Here we develop an array of micro-electro-mechanical systems (MEMS) resonant mass sensors that can be used to directly measure the biophysical properties, mass, and growth rate of single adherent cells. Unlike conventional cantilever mass sensors, our sensors retain a uniform mass sensitivity over the cell attachment surface. By measuring the frequency shift of the mass sensors with growing (soft) cells and fixed (stiff) cells, and through analytical modeling, we derive the Young's modulus of the unfixed cell and unravel the dependence of the cell mass measurement on cell stiffness. Finally, we grew individual cells on the mass sensors and measured their mass for 50+ hours. Our results demonstrate that adherent human colon epithelial cells have increased growth rates with a larger cell mass, and the average growth rate increases linearly with the cell mass, at 3.25%/hr. Our sensitive mass sensors with a position-independent mass sensitivity can be coupled with microscopy for simultaneous monitoring of cell growth and status, and provide an ideal method to study cell growth, cell cycle progression, differentiation, and apoptosis.


Assuntos
Tamanho Celular , Sistemas Microeletromecânicos/métodos , Técnicas Biossensoriais , Adesão Celular , Proliferação de Células , Células HT29 , Humanos , Fatores de Tempo
20.
Nano Lett ; 10(10): 3927-32, 2010 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-20825204

RESUMO

Semiconductor micro- and nanotubes can be formed by strain-induced self-rolling of membranes. The effect of geometrical dimensions on the self-rolling behavior of epitaxial mismatch-strained In(x)Ga(1-x)As-GaAs membranes are systematically studied both experimentally and theoretically using the finite element method. The final rolling direction depends on the length and width of the membrane as well as the diameter of the rolled-up tube. The energetics of the final states, the history of rolling process, and the kinetic control of the etching anisotropy ultimately determine the rolling behavior. Results reported here provide critical information for precise positioning and uniform large area assembly of semiconducting micro- and nanotubes for applications in photonics, microelectromechanical systems, etc.

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