共查询到20条相似文献，搜索用时 0 毫秒
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Masoud Khabiry Bong Geun Chung Matthew J. Hancock Harish Chandra Soundararajan Yanan Du Donald Cropek Won Gu Lee Ali Khademhosseini 《Small (Weinheim an der Bergstrasse, Germany)》2009,5(10):1186-1194
Microstructures that generate shear‐protected regions in microchannels can rapidly immobilize cells for cell‐based biosensing and drug screening. Here, a two‐step fabrication method is used to generate double microgrooves with various depth ratios to achieve controlled double‐level cell patterning while still providing shear protection. Six microgroove geometries are fabricated with different groove widths and depth ratios. Two modes of cell docking are observed: cells docked upstream in sufficiently deep and narrow grooves, and downstream in shallow, wide grooves. Computational flow simulations link the groove geometry and bottom shear stress to the experimental cell docking patterns. Analysis of the experimental cell retention in the double grooves demonstrates its linear dependence on inlet flow speed, with slope inversely proportional to the sheltering provided by the groove geometry. Thus, double‐grooved microstructures in microfluidic channels provide shear‐protected regions for cell docking and immobilization and appear promising for cell‐based biosensing and drug discovery. 相似文献
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Ruiguo Yang Vincent Lemaître Changjin Huang Abbas Haddadi Rebecca McNaughton Horacio D. Espinosa 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(12)
Stably transfected cell lines are widely used in drug discovery and biological research to produce recombinant proteins. Generation of these cell lines requires the isolation of multiple clones, using time‐consuming dilution methods, to evaluate the expression levels of the gene of interest. A new and efficient method is described for the generation of monoclonal cell lines, without the need for dilution cloning. In this new method, arrays of patterned cell colonies and single cell transfection are employed to deliver a plasmid coding for a reporter gene and conferring resistance to an antibiotic. Using a nanofountain probe electroporation system, probe positioning is achieved through a micromanipulator with sub‐micron resolution and resistance‐based feedback control. The array of patterned cell colonies allows for rapid selection of numerous stably transfected clonal cell lines located on the same culture well, conferring a significant advantage over slower and labor‐intensive traditional methods. In addition to plasmid integration, this methodology can be seamlessly combined with CRISPR/Cas9 gene editing, paving the way for advanced cell engineering. 相似文献
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Kenza Samlali Fatemeh Ahmadi Angela B. V. Quach Guy Soffer Steve C. C. Shih 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(34)
Generating a stable knockout cell line is a complex process that can take several months to complete. In this work, a microfluidic method that is capable of isolating single cells in droplets, selecting successful edited clones, and expansion of these isoclones is introduced. Using a hybrid microfluidics method, droplets in channels can be individually addressed using a co‐planar electrode system. In the hybrid microfluidics device, it is shown that single cells can be trapped and subsequently encapsulate them on demand into pL‐sized droplets. Furthermore, droplets containing single cells are either released, kept in the traps, or merged with other droplets by the application of an electric potential to the electrodes that is actuated through an in‐house user interface. This high precision control is used to successfully sort and recover single isoclones to establish monoclonal cell lines, which is demonstrated with a heterozygous NCI‐H1299 lung squamous cell population resulting from loss‐of‐function eGFP and RAF1 gene knockout transfections. 相似文献
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Lang Nan Man Yuk Alison Lai Matthew Yuk Heng Tang Yau Kei Chan Leo Lit Man Poon Ho Cheung Shum 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(9)
Droplet‐based microfluidic techniques are extensively used in efficient manipulation and genome‐wide analysis of individual cells, probing the heterogeneity among populations of individuals. However, the extraction and isolation of single cells from individual droplets remains difficult due to the inevitable sample loss during processing. Herein, an automated system for accurate collection of defined numbers of droplets containing single cells is presented. Based on alternate sorting and dispensing in three branch channels, the droplet number can be precisely controlled down to single‐droplet resolution. While encapsulating single cells and reserving one branch as a waste channel, sorting can be seamlessly integrated to enable on‐demand collection of single cells. Combined with a lossless recovery strategy, this technique achieves capture and culture of individual cells with a harvest rate of over 95%. The on‐demand droplet collection technique has great potential to realize quantitative processing and analysis of single cells for elucidating the role of cell‐to‐cell variations. 相似文献
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Scott C. Lenaghan Stefan Nwandu-Vincent Benjamin E. Reese Mingjun Zhang 《Journal of the Royal Society Interface》2014,11(93)
In this work, a high-speed imaging platform and a resistive force theory (RFT) based model were applied to investigate multi-flagellated propulsion, using Tritrichomonas foetus as an example. We discovered that T. foetus has distinct flagellar beating motions for linear swimming and turning, similar to the ‘run and tumble’ strategies observed in bacteria and Chlamydomonas. Quantitative analysis of the motion of each flagellum was achieved by determining the average flagella beat motion for both linear swimming and turning, and using the velocity of the flagella as inputs into the RFT model. The experimental approach was used to calculate the curvature along the length of the flagella throughout each stroke. It was found that the curvatures of the anterior flagella do not decrease monotonically along their lengths, confirming the ciliary waveform of these flagella. Further, the stiffness of the flagella was experimentally measured using nanoindentation, allowing for calculation of the flexural rigidity of T. foetus''s flagella, 1.55×10−21 N m2. Finally, using the RFT model, it was discovered that the propulsive force of T. foetus was similar to that of sperm and Chlamydomonas, indicating that multi-flagellated propulsion does not necessarily contribute to greater thrust generation, and may have evolved for greater manoeuvrability or sensing. The results from this study have demonstrated the highly coordinated nature of multi-flagellated propulsion and have provided significant insights into the biology of T. foetus. 相似文献
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The present state of the standard base of Russia for measuring small direct-current in the 10−16–10−9 A range is considered, and the metrological characteristics of the state primary and transferable standards are given.
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Translated from Izmeritel’naya Tekhnika, No. 11, pp. 40–42, November, 2007. 相似文献
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Maximilian Grsche Ahmed E. Zoheir Johannes Stegmaier Ralf Mikut Dario Mager Jan G. Korvink Kersten S. Rabe Christof M. Niemeyer 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(35)
Microfluidic water‐in‐oil droplets are a versatile tool for biological and biochemical applications due to the advantages of extremely small monodisperse reaction vessels in the pL–nL range. A key factor for the successful dissemination of this technology to life science laboratory users is the ability to produce microfluidic droplet generators and related accessories by low‐entry barrier methods, which enable rapid prototyping and manufacturing of devices with low instrument and material costs. The direct, experimental side‐by‐side comparison of three commonly used additive manufacturing (AM) methods, namely fused deposition modeling (FDM), inkjet printing (InkJ), and stereolithography (SLA), is reported. As a benchmark, micromilling (MM) is used as an established method. To demonstrate which of these methods can be easily applied by the non‐expert to realize applications in topical fields of biochemistry and microbiology, the methods are evaluated with regard to their limits for the minimum structure resolution in all three spatial directions. The suitability of functional SLA and MM chips to replace classic SU‐8 prototypes is demonstrated on the basis of representative application cases. 相似文献
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Anna Liu Tong Yu Katherine Young Nicholas Stone Srinivas Hanasoge Tyler J. Kirby Vikram Varadarajan Nicholas Colonna Janet Liu Abhishek Raj Jan Lammerding Alexander Alexeev Todd Sulchek 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(2)
Cells respond to mechanical forces by deforming in accordance with viscoelastic solid behavior. Studies of microscale cell deformation observed by high speed video microscopy have elucidated a new cell behavior in which sufficiently rapid mechanical compression of cells can lead to transient cell volume loss and then recovery. This work has discovered that the resulting volume exchange between the cell interior and the surrounding fluid can be utilized for efficient, convective delivery of large macromolecules (2000 kDa) to the cell interior. However, many fundamental questions remain about this cell behavior, including the range of deformation time scales that result in cell volume loss and the physiological effects experienced by the cell. In this study, a relationship is established between cell viscoelastic properties and the inertial forces imposed on the cell that serves as a predictor of cell volume loss across human cell types. It is determined that cells maintain nuclear envelope integrity and demonstrate low protein loss after the volume exchange process. These results define a highly controlled cell volume exchange mechanism for intracellular delivery of large macromolecules that maintains cell viability and function for invaluable downstream research and clinical applications. 相似文献
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《Small Methods》2017,1(10)
Single‐cell analyses of secretory proteins are essential to fully understand cellular functional heterogeneity and unravel the underlying mechanisms of intercellular signaling and interactions. Retrieving dynamic information of protein secretion at single‐cell resolution reflects the precise, real‐time functional states of individual cells in physiological processes. Such measurements remain very challenging in single‐cell analysis, which requires highly integrated systems capable of performing on‐chip single‐cell isolation and subsequent real‐time protein detection. Here, recent advances in microfluidics‐based single‐cell manipulation and emerging approaches for label‐free single‐cell biosensing are reviewed. The advantages and limitations of these technologies are summarized and challenges to establish the integrated microfluidic biosensing systems for real‐time single‐cell secretomics are discussed. Recent efforts on integrated platforms for on‐chip single‐cell protein assays are highlighted and some perspectives on future directions in this field are provided. 相似文献
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Shuhuan Hu Guangyu Liu Weiqiang Chen Xiang Li Wei Lu Raymond H. W. Lam Jianping Fu 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(17):2300-2311
Deep phenotyping of single cancer cells is of critical importance in the era of precision medicine to advance understanding of relationships between gene mutation and cell phenotype and to elucidate the biological nature of tumor heterogeneity. Existing microfluidic single‐cell phenotyping tools, however, are limited to phenotypic measurements of 1–2 selected morphological and physiological features of single cells. Herein a microfluidic elasticity microcytometer is reported for multiparametric biomechanical and biochemical phenotypic profiling of free‐floating, live single cancer cells for quantitative, simultaneous characterizations of cell size, cell deformability/stiffness, and surface receptors. The elasticity microcytometer is implemented for measurements and comparisons of four human cell lines with distinct metastatic potentials and derived from different human tissues. An analytical model is developed from first principles for the first time to convert cell deformation and adhesion information of single cancer cells encapsulated inside the elasticity microcytometer to cell deformability/stiffness and surface protein expression. Together, the elasticity microcytometer holds great promise for comprehensive molecular, cellular, and biomechanical phenotypic profiling of live cancer cells at the single cell level, critical for studying intratumor cellular and molecular heterogeneity using low‐abundance, clinically relevant human cancer cells. 相似文献
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Cell Phenotyping: Multiparametric Biomechanical and Biochemical Phenotypic Profiling of Single Cancer Cells Using an Elasticity Microcytometer (Small 17/2016) 
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下载免费PDF全文 Shuhuan Hu Guangyu Liu Weiqiang Chen Xiang Li Wei Lu Raymond H. W. Lam Jianping Fu 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(17):2247-2247
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Kim SH Yamamoto T Fourmy D Fujii T 《Small (Weinheim an der Bergstrasse, Germany)》2011,7(22):3239-3247
We present a novel method, implemented in the form of a microfluidic device, for arraying and analyzing large populations of single cells. The device contains a large array of electroactive microwells where manipulation and analysis of large population of cells are carried out. On the device, single cells can be actively trapped in the microwells by dielectrophoresis (DEP) and then lysed by electroporation (EP) for subsequent analysis of the confined cell lysates. The DEP force in the selected dimensions of the microwells could achieve efficient trapping in nearly all the microwells (95%) in less than three minutes. Moreover, the positions of the cells in the microwells are maintained even when unstable flow of liquid is applied. This makes it possible to exchange the DEP buffer to a solution that will be subsequently used for stimulating or analyzing the trapped cells. After closing the microwells, EP is conducted to lyse the trapped cells by applying short electric pulses. Tight enclosure is critical to prevent dilution, diffusion and cross contamination of the cell lysates. We demonstrated the feasibility of our approach with an enzymatic assay measuring the intracellular-galactosidase activity. The use of this method should greatly help analysis of large populations of cells at the single-cell level. Furthermore, the method offers rapidity in the trapping and analysis of multiple cell types in physiological conditions that will be important to ensure the relevance of single cell analyses. 相似文献
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Idan Gal Reuven Edri Nadav Noor Matan Rotenberg Michael Namestnikov Itai Cabilly Assaf Shapira Tal Dvir 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(8)
One of the strategies for heart regeneration includes cell delivery to the defected heart. However, most of the injected cells do not form quick cell–cell or cell–matrix interactions, therefore, their ability to engraft at the desired site and improve heart function is poor. Here, the use of a microfluidic system is reported for generating personalized hydrogel‐based cellular microdroplets for cardiac cell delivery. To evaluate the system's limitations, a mathematical model of oxygen diffusion and consumption within the droplet is developed. Following, the microfluidic system's parameters are optimized and cardiac cells from neonatal rats or induced pluripotent stem cells are encapsulated. The morphology and cardiac specific markers are assessed and cell function within the droplets is analyzed. Finally, the cellular droplets are injected to mouse gastrocnemius muscle to validate cell retention, survival, and maturation within the host tissue. These results demonstrate the potential of this approach to generate personalized cellular microtissues, which can be injected to distinct regions in the body for treating damaged tissues. 相似文献
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Xuan Li Mohammad Aghaamoo Shiyue Liu Do‐Hyun Lee Abraham P. Lee 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(40)
While lipoplex (cationic lipid‐nucleic acid complex)‐mediated intracellular delivery is widely adopted in mammalian cell transfection, its transfection efficiency for suspension cells, e.g., lymphatic and hematopoietic cells, is reported at only ≈5% or even lower. Here, efficient and consistent lipoplex‐mediated transfection is demonstrated for hard‐to‐transfect suspension cells via a single‐cell, droplet‐microfluidics approach. In these microdroplets, monodisperse lipoplexes for effective gene delivery are generated via chaotic mixing induced by the serpentine microchannel and co‐confined with single cells. Moreover, the cell membrane permeability increases due to the shear stress exerted on the single cells when they pass through the droplet pinch‐off junction. The transfection efficiency, examined by the delivery of the pcDNA3‐EGFP plasmid, improves from ≈5% to ≈50% for all three tested suspension cell lines, i.e., K562, THP‐1, Jurkat, and with significantly reduced cell‐to‐cell variation, compared to the bulk method. Efficient targeted knockout of the TP53BP1 gene for K562 cells via the CRISPR (clustered regularly interspaced short palindromic repeats)–CAS9 (CRISPR‐associated nuclease 9) mechanism is also achieved using this platform. Lipoplex‐mediated single‐cell transfection via droplet microfluidics is expected to have broad applications in gene therapy and regenerative medicine by providing high transfection efficiency and low cell‐to‐cell variation for hard‐to‐transfect suspension cells. 相似文献
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Sofia Nahavandi Shi‐Yang Tang Sara Baratchi Rebecca Soffe Saeid Nahavandi Kourosh Kalantar‐zadeh Arnan Mitchell Khashayar Khoshmanesh 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(23):4810-4826
Intercellular signalling has been identified as a highly complex process, responsible for orchestrating many physiological functions. While conventional methods of investigation have been useful, their limitations are impeding further development. Microfluidics offers an opportunity to overcome some of these limitations. Most notably, microfluidic systems can emulate the in‐vivo environments. Further, they enable exceptionally precise control of the microenvironment, allowing complex mechanisms to be selectively isolated and studied in detail. There has thus been a growing adoption of microfluidic platforms for investigation of cell signalling mechanisms. This review provides an overview of the different signalling mechanisms and discusses the methods used to study them, with a focus on the microfluidic devices developed for this purpose. 相似文献