1
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Holler C, Taylor RW, Schambony A, Möckl L, Sandoghdar V. A paintbrush for delivery of nanoparticles and molecules to live cells with precise spatiotemporal control. Nat Methods 2024; 21:512-520. [PMID: 38347139 PMCID: PMC10927540 DOI: 10.1038/s41592-024-02177-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 01/08/2024] [Indexed: 03/13/2024]
Abstract
Delivery of very small amounts of reagents to the near-field of cells with micrometer spatial precision and millisecond time resolution is currently out of reach. Here we present μkiss as a micropipette-based scheme for brushing a layer of small molecules and nanoparticles onto the live cell membrane from a subfemtoliter confined volume of a perfusion flow. We characterize our system through both experiments and modeling, and find excellent agreement. We demonstrate several applications that benefit from a controlled brush delivery, such as a direct means to quantify local and long-range membrane mobility and organization as well as dynamical probing of intercellular force signaling.
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Affiliation(s)
- Cornelia Holler
- Max Planck Institute for the Science of Light, Erlangen, Germany
- Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany
- Department of Biology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Richard William Taylor
- Max Planck Institute for the Science of Light, Erlangen, Germany
- Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany
| | - Alexandra Schambony
- Max Planck Institute for the Science of Light, Erlangen, Germany
- Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany
- Department of Biology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Leonhard Möckl
- Max Planck Institute for the Science of Light, Erlangen, Germany
| | - Vahid Sandoghdar
- Max Planck Institute for the Science of Light, Erlangen, Germany.
- Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany.
- Department of Physics, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany.
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2
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Taylor DP, Mathur P, Renaud P, Kaigala GV. Microscale hydrodynamic confinements: shaping liquids across length scales as a toolbox in life sciences. LAB ON A CHIP 2022; 22:1415-1437. [PMID: 35348555 DOI: 10.1039/d1lc01101d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Hydrodynamic phenomena can be leveraged to confine a range of biological and chemical species without needing physical walls. In this review, we list methods for the generation and manipulation of microfluidic hydrodynamic confinements in free-flowing liquids and near surfaces, and elucidate the associated underlying theory and discuss their utility in the emerging area of open space microfluidics applied to life-sciences. Microscale hydrodynamic confinements are already starting to transform approaches in fundamental and applied life-sciences research from precise separation and sorting of individual cells, allowing localized bio-printing to multiplexing for clinical diagnosis. Through the choice of specific flow regimes and geometrical boundary conditions, hydrodynamic confinements can confine species across different length scales from small molecules to large cells, and thus be applied to a wide range of functionalities. We here provide practical examples and implementations for the formation of these confinements in different boundary conditions - within closed channels, in between parallel plates and in an open liquid volume. Further, to enable non-microfluidics researchers to apply hydrodynamic flow confinements in their work, we provide simplified instructions pertaining to their design and modelling, as well as to the formation of hydrodynamic flow confinements in the form of step-by-step tutorials and analytical toolbox software. This review is written with the idea to lower the barrier towards the use of hydrodynamic flow confinements in life sciences research.
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Affiliation(s)
- David P Taylor
- IBM Research - Europe, Säumerstrasse 4, 8803 Rüschlikon, Switzerland.
- Microsystems Laboratory 4, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Prerit Mathur
- IBM Research - Europe, Säumerstrasse 4, 8803 Rüschlikon, Switzerland.
- Dept. of Chemistry and Applied Biosciences, Eidgenössische Technische Hochschule (ETH), Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland
| | - Philippe Renaud
- Microsystems Laboratory 4, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Govind V Kaigala
- IBM Research - Europe, Säumerstrasse 4, 8803 Rüschlikon, Switzerland.
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3
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Taylor DP, Kaigala GV. Reconfigurable microfluidics: real-time shaping of virtual channels through hydrodynamic forces. LAB ON A CHIP 2020; 20:1720-1728. [PMID: 32253402 DOI: 10.1039/d0lc00197j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
To break the current paradigm in microfluidics that directly links device design to functionality, we introduce microfluidic "virtual channels" that can be dynamically shaped in real-time. A virtual channel refers to a flow path within a microfluidic flow cell, guiding an injected reagent along a user-defined trajectory solely by hydrodynamic forces. Virtual channels dynamically reproduce key microfluidic functionality: directed transport of minute volumes of liquid, splitting, merging and mixing of flows. Virtual channels can be formed directly on standard biological substrates, which we demonstrate by sequential immunodetection at arrays of individual reaction sites on a glass slide and by alternating between local and global processing of surface-adherent cell-block sections. This approach is simple, versatile and generic enough to form the basis of a new class of microfluidic techniques.
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Affiliation(s)
- David P Taylor
- Laboratory of Microsystems LMIS4, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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4
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Verlinden EJ, Madadelahi M, Sarajlic E, Shamloo A, Engel AH, Staufer U, Ghatkesar MK. Volume and concentration dosing in picolitres using a two-channel microfluidic AFM cantilever. NANOSCALE 2020; 12:10292-10305. [PMID: 32363366 DOI: 10.1039/c9nr10494a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We introduce a two-channel microfluidic atomic force microscopy (AFM) cantilever that combines the nanomechanical sensing functionality of an AFM cantilever with the ability to manipulate fluids of picolitres or smaller volumes through nanoscale apertures near the cantilever tip. Each channel is connected to a separate fluid reservoir, which can be independently controlled by pressure. Various systematic experiments with fluorescent liquids were done by either injecting the liquids from the on-chip reservoir or aspirating directly through the nanoscale apertures at the tip. A flow rate analysis of volume dosing, aspiration and concentration dosing inside the liquid medium was performed. To understand the fluid behaviour, an analytical model based on the hydrodynamic resistance, as well as numerical flow simulations of single and multi-phase conditions were performed and compared. By applying pressures between -500 mbar and 500 mbar to the reservoirs of the probe with respect to the ambient pressure, flow rates ranging from 10 fl s-1 to 83 pl s-1 were obtained inside the channels of the cantilever as predicted by the analytical model. The smallest dosing flow rate through the apertures was 720 fl s-1, which was obtained with a 10 mbar pressure on one reservoir and ambient pressure on the other. The solute concentration in the outflow could be tuned to values between 0% and 100% by pure convection and to values between 17.5% and 90% in combination with diffusion. The results prove that this new probe enables handling multiple fluids with the scope to inject different concentrations of analytes inside a single living cell and also perform regular AFM functionalities.
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Affiliation(s)
- E J Verlinden
- Department of Precision and Microsystems Engineering, Delft University of Technology, The Netherlands.
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5
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Taylor DP, Kaigala GV. Fluidic Bypass Structures for Improving the Robustness of Liquid Scanning Probes. IEEE Trans Biomed Eng 2019; 66:2491-2498. [DOI: 10.1109/tbme.2018.2890602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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6
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Zhang Q, Mao S, Khan M, Feng S, Zhang W, Li W, Lin JM. In Situ Partial Treatment of Single Cells by Laminar Flow in the “Open Space”. Anal Chem 2018; 91:1644-1650. [DOI: 10.1021/acs.analchem.8b05313] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Qiang Zhang
- Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Tsinghua University, Beijing 100084, China
| | - Sifeng Mao
- Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Tsinghua University, Beijing 100084, China
| | - Mashooq Khan
- Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Tsinghua University, Beijing 100084, China
| | - Shuo Feng
- Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Tsinghua University, Beijing 100084, China
| | - Wanling Zhang
- Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Tsinghua University, Beijing 100084, China
| | - Weiwei Li
- Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Tsinghua University, Beijing 100084, China
| | - Jin-Ming Lin
- Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Tsinghua University, Beijing 100084, China
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7
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Mao S, Zhang Q, Liu W, Huang Q, Khan M, Zhang W, Lin C, Uchiyama K, Lin JM. Chemical operations on a living single cell by open microfluidics for wound repair studies and organelle transport analysis. Chem Sci 2018; 10:2081-2087. [PMID: 30881632 PMCID: PMC6381548 DOI: 10.1039/c8sc05104f] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 11/27/2018] [Indexed: 12/18/2022] Open
Abstract
We report a laminar flow based approach that is capable of precisely cutting off or treating a portion of a single cell from its remaining portion in its original adherent state.
Single cells are increasingly recognized to be capable of wound repair that is important for our mechanistic understanding of cell biology. The lack of flexible, facile, and friendly subcellular treatment methods has hindered single-cell wound repair studies and organelle transport analyses. Here we report a laminar flow based approach, we call it fluid cell knife (Fluid CK), that is capable of precisely cutting off or treating a portion of a single cell from its remaining portion in its original adherent state. Local operations on portions of a living single cell in its adherent culture state were applied to various types of cells. Temporal wound repair was successfully observed. Moreover, we successfully stained portions of a living single cell to measure the organelle transport speed (mitochondria as a model) inside a cell. This technique opens up new avenues for cellular wound repair and subcellular behavior analyses.
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Affiliation(s)
- Sifeng Mao
- Department of Chemistry , Beijing Key Laboratory of Microanalytical Methods and Instrumentation , MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology , Tsinghua University , Beijing 100084 , China .
| | - Qiang Zhang
- Department of Chemistry , Beijing Key Laboratory of Microanalytical Methods and Instrumentation , MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology , Tsinghua University , Beijing 100084 , China .
| | - Wu Liu
- Department of Chemistry , Beijing Key Laboratory of Microanalytical Methods and Instrumentation , MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology , Tsinghua University , Beijing 100084 , China .
| | - Qiushi Huang
- Department of Chemistry , Beijing Key Laboratory of Microanalytical Methods and Instrumentation , MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology , Tsinghua University , Beijing 100084 , China .
| | - Mashooq Khan
- Department of Chemistry , Beijing Key Laboratory of Microanalytical Methods and Instrumentation , MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology , Tsinghua University , Beijing 100084 , China .
| | - Wanling Zhang
- Department of Chemistry , Beijing Key Laboratory of Microanalytical Methods and Instrumentation , MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology , Tsinghua University , Beijing 100084 , China .
| | - Caihou Lin
- Department of Neurosurgery , Fujian Medical University Union Hospital , Fuzhou , Fujian 350001 , China
| | - Katsumi Uchiyama
- Department of Applied Chemistry , Graduate School of Urban Environmental Sciences , Tokyo Metropolitan University , Minamiohsawa , Hachioji , Tokyo 192-0397 , Japan
| | - Jin-Ming Lin
- Department of Chemistry , Beijing Key Laboratory of Microanalytical Methods and Instrumentation , MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology , Tsinghua University , Beijing 100084 , China .
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8
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Mao S, Zhang Y, Zhang Q, Lin JM, Uchiyama K. Local surface modification at precise position using a chemical pen. Talanta 2018; 187:246-251. [PMID: 29853042 DOI: 10.1016/j.talanta.2018.05.044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 05/10/2018] [Accepted: 05/11/2018] [Indexed: 11/17/2022]
Abstract
Push-pull cannula system, which was first proposed by Gaddum, has grown to be an important method for the perfusion of brain and region-selective surface treatment. However, reported push-pull cannula systems only concerned on single reagent applications. Microfluidic system was then an exciting tool for multi-reagent treatment on substrate in closed microchannels. Nowadays, it is still a challenge to apply online mixing and reaction for surface pattern in an open environment. Here, we present a novel method using a chemical pen that enables region-selective online chemical reactions for the micro-surface modification/patterning. We utilized this method to fabricate labeling protein array using an online labeling strategy. Moreover, the device was applied for local modification of biomaterials surface by using a three-component reaction at precise position. This tool was the first demonstration of design to perform online reaction of two different reagents on a real solid sample in an open environment. It was demonstrated a useful method for protein array fabrication with online labeled protein.
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Affiliation(s)
- Sifeng Mao
- Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Tsinghua University, Beijing 100084, China
| | - Yong Zhang
- Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, Minamiohsawa, Hachioji 192-0362, Tokyo
| | - Qiang Zhang
- Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Tsinghua University, Beijing 100084, China
| | - Jin-Ming Lin
- Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Tsinghua University, Beijing 100084, China.
| | - Katsumi Uchiyama
- Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, Minamiohsawa, Hachioji 192-0362, Tokyo.
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9
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Gao Y, Li B, Singhal R, Fontecchio A, Pelleg B, Orynbayeva Z, Gogotsi Y, Friedman G. Perfusion double-channel micropipette probes for oxygen flux mapping with single-cell resolution. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2018; 9:850-860. [PMID: 29600146 PMCID: PMC5852649 DOI: 10.3762/bjnano.9.79] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 02/21/2018] [Indexed: 06/08/2023]
Abstract
Measuring cellular respiration with single-cell spatial resolution is a significant challenge, even with modern tools and techniques. Here, a double-channel micropipette is proposed and investigated as a probe to achieve this goal by sampling fluid near the point of interest. A finite element model (FEM) of this perfusion probe is validated by comparing simulation results with experimental results of hydrodynamically confined fluorescent molecule diffusion. The FEM is then used to investigate the dependence of the oxygen concentration variation and the measurement signal on system parameters, including the pipette's shape, perfusion velocity, position of the oxygen sensors within the pipette, and proximity of the pipette to the substrate. The work demonstrates that the use of perfusion double-barrel micropipette probes enables the detection of oxygen consumption signals with micrometer spatial resolution, while amplifying the signal, as compared to sensors without the perfusion system. In certain flow velocity ranges (depending on pipette geometry and configuration), the perfusion flow increases oxygen concentration gradients formed due to cellular oxygen consumption. An optimal perfusion velocity for respiratory measurements on single cells can be determined for different system parameters (e.g., proximity of the pipette to the substrate). The optimum perfusion velocities calculated in this paper range from 1.9 to 12.5 μm/s. Finally, the FEM model is used to show that the spatial resolution of the probe may be varied by adjusting the pipette tip diameter, which may allow oxygen consumption mapping of cells within tissue, as well as individual cells at subcellular resolution.
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Affiliation(s)
- Yang Gao
- Department of Electrical and Computer Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA
| | - Bin Li
- Department of Electrical and Computer Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA
| | - Riju Singhal
- Department of Material Science and Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA
| | - Adam Fontecchio
- Department of Electrical and Computer Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA
| | - Ben Pelleg
- Department of Electrical and Computer Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA
| | - Zulfiya Orynbayeva
- Department of Surgery, Drexel University, 245 N. 15th Street, Philadelphia, PA 19102, USA
| | - Yury Gogotsi
- Department of Material Science and Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA
| | - Gary Friedman
- Department of Electrical and Computer Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA
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10
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Aebersold MJ, Dermutz H, Demkó L, Cogollo JFS, Lin SC, Burchert C, Schneider M, Ling D, Forró C, Han H, Zambelli T, Vörös J. Local Chemical Stimulation of Neurons with the Fluidic Force Microscope (FluidFM). Chemphyschem 2017; 19:1234-1244. [DOI: 10.1002/cphc.201700780] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 10/06/2017] [Indexed: 01/06/2023]
Affiliation(s)
- Mathias J. Aebersold
- Laboratory of Biosensors and Bioelectronics; Institute for Biomedical Engineering, University and ETH Zurich; Gloriastrasse 35 8092 Zurich Switzerland
| | - Harald Dermutz
- Laboratory of Biosensors and Bioelectronics; Institute for Biomedical Engineering, University and ETH Zurich; Gloriastrasse 35 8092 Zurich Switzerland
| | - László Demkó
- Laboratory of Biosensors and Bioelectronics; Institute for Biomedical Engineering, University and ETH Zurich; Gloriastrasse 35 8092 Zurich Switzerland
| | - José F. Saenz Cogollo
- Laboratory of Biosensors and Bioelectronics; Institute for Biomedical Engineering, University and ETH Zurich; Gloriastrasse 35 8092 Zurich Switzerland
| | - Shiang-Chi Lin
- Laboratory of Biosensors and Bioelectronics; Institute for Biomedical Engineering, University and ETH Zurich; Gloriastrasse 35 8092 Zurich Switzerland
| | - Conrad Burchert
- Laboratory of Biosensors and Bioelectronics; Institute for Biomedical Engineering, University and ETH Zurich; Gloriastrasse 35 8092 Zurich Switzerland
| | - Moritz Schneider
- Laboratory of Biosensors and Bioelectronics; Institute for Biomedical Engineering, University and ETH Zurich; Gloriastrasse 35 8092 Zurich Switzerland
| | - Doris Ling
- Laboratory of Biosensors and Bioelectronics; Institute for Biomedical Engineering, University and ETH Zurich; Gloriastrasse 35 8092 Zurich Switzerland
| | - Csaba Forró
- Laboratory of Biosensors and Bioelectronics; Institute for Biomedical Engineering, University and ETH Zurich; Gloriastrasse 35 8092 Zurich Switzerland
| | - Hana Han
- Laboratory of Biosensors and Bioelectronics; Institute for Biomedical Engineering, University and ETH Zurich; Gloriastrasse 35 8092 Zurich Switzerland
| | - Tomaso Zambelli
- Laboratory of Biosensors and Bioelectronics; Institute for Biomedical Engineering, University and ETH Zurich; Gloriastrasse 35 8092 Zurich Switzerland
| | - János Vörös
- Laboratory of Biosensors and Bioelectronics; Institute for Biomedical Engineering, University and ETH Zurich; Gloriastrasse 35 8092 Zurich Switzerland
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11
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Stern S, Rotem A, Burnishev Y, Weinreb E, Moses E. External Excitation of Neurons Using Electric and Magnetic Fields in One- and Two-dimensional Cultures. J Vis Exp 2017. [PMID: 28518110 DOI: 10.3791/54357] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
A neuron will fire an action potential when its membrane potential exceeds a certain threshold. In typical activity of the brain, this occurs as a result of chemical inputs to its synapses. However, neurons can also be excited by an imposed electric field. In particular, recent clinical applications activate neurons by creating an electric field externally. It is therefore of interest to investigate how the neuron responds to the external field and what causes the action potential. Fortunately, precise and controlled application of an external electric field is possible for embryonic neuronal cells that are excised, dissociated and grown in cultures. This allows the investigation of these questions in a highly reproducible system. In this paper some of the techniques used for controlled application of external electric field on neuronal cultures are reviewed. The networks can be either one dimensional, i.e. patterned in linear forms or allowed to grow on the whole plane of the substrate, and thus two dimensional. Furthermore, the excitation can be created by the direct application of electric field via electrodes immersed in the fluid (bath electrodes) or by inducing the electric field using the remote creation of magnetic pulses.
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Affiliation(s)
- Shani Stern
- Laboratory of Genetics, The Salk Institute for Biological Studies
| | - Assaf Rotem
- Department of Physics and SEAS, Harvard University
| | - Yuri Burnishev
- Department of Physics of Complex Systems, Weizmann Institute of Science
| | - Eyal Weinreb
- Department of Physics of Complex Systems, Weizmann Institute of Science
| | - Elisha Moses
- Department of Physics of Complex Systems, Weizmann Institute of Science;
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12
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Autebert J, Cors JF, Taylor DP, Kaigala GV. Convection-Enhanced Biopatterning with Recirculation of Hydrodynamically Confined Nanoliter Volumes of Reagents. Anal Chem 2016; 88:3235-42. [PMID: 26837532 PMCID: PMC4794703 DOI: 10.1021/acs.analchem.5b04649] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
![]()
We
present a new methodology for efficient and high-quality patterning
of biological reagents for surface-based biological assays. The method
relies on hydrodynamically confined nanoliter volumes of reagents
to interact with the substrate at the micrometer-length scale. We
study the interplay between diffusion, advection, and surface chemistry
and present the design of a noncontact scanning microfluidic device
to efficiently present reagents on surfaces. By leveraging convective
flows, recirculation, and mixing of a processing liquid, this device
overcomes limitations of existing biopatterning approaches, such as
passive diffusion of analytes, uncontrolled wetting, and drying artifacts.
We demonstrate the deposition of analytes, showing a 2- to 5-fold
increase in deposition rate together with a 10-fold reduction in analyte
consumption while ensuring less than 6% variation in pattern homogeneity
on a standard biological substrate. In addition, we demonstrate the
recirculation of a processing liquid using a microfluidic probe (MFP)
in the context of a surface assay for (i) probing 12 independent areas
with a single microliter of processing liquid and (ii) processing
a 2 mm2 surface to create 170 antibody spots of 50 ×
100 μm2 area using 1.6 μL of liquid. We observe
high pattern quality, conservative usage of reagents, micrometer precision
of localization and convection-enhanced fast deposition. Such a device
and method may facilitate quantitative biological assays and spur
the development of the next generation of protein microarrays.
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Affiliation(s)
- Julien Autebert
- IBM Research-Zurich , Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Julien F Cors
- IBM Research-Zurich , Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - David P Taylor
- IBM Research-Zurich , Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Govind V Kaigala
- IBM Research-Zurich , Säumerstrasse 4, 8803 Rüschlikon, Switzerland
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13
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Autebert J, Kashyap A, Lovchik RD, Delamarche E, Kaigala GV. Hierarchical hydrodynamic flow confinement: efficient use and retrieval of chemicals for microscale chemistry on surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:3640-5. [PMID: 24625080 PMCID: PMC4213896 DOI: 10.1021/la500875m] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We devised, implemented, and tested a new concept for efficient local surface chemistry that we call hierarchical hydrodynamic flow confinement (hierarchical HFC). This concept leverages the hydrodynamic shaping of multiple layers of liquid to address challenges inherent to microscale surface chemistry, such as minimal dilution, economical consumption of reagent, and fast liquid switching. We illustrate two modes of hierarchical HFC, nested and pinched, by locally denaturing and recovering a 26 bp DNA with as little as 2% dilution and by efficiently patterning an antibody on a surface, with a 5 μm resolution and a 100-fold decrease of reagent consumption compared to microcontact printing. In addition, valveless switching between nanoliter volumes of liquids was achieved within 20 ms. We believe hierarchical HFC will have broad utility for chemistry on surfaces at the microscale.
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14
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Kaigala GV, Lovchik RD, Delamarche E. Microfluidics in the "open space" for performing localized chemistry on biological interfaces. Angew Chem Int Ed Engl 2013; 51:11224-40. [PMID: 23111955 DOI: 10.1002/anie.201201798] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Local interactions between (bio)chemicals and biological interfaces play an important role in fields ranging from surface patterning to cell toxicology. These interactions can be studied using microfluidic systems that operate in the "open space", that is, without the need for the sealed channels and chambers commonly used in microfluidics. This emerging class of techniques localizes chemical reactions on biological interfaces or specimens without imposing significant "constraints" on samples, such as encapsulation, pre-processing steps, or the need for scaffolds. They therefore provide new opportunities for handling, analyzing, and interacting with biological samples. The motivation for performing localized chemistry is discussed, as are the requirements imposed on localization techniques. Three classes of microfluidic systems operating in the open space, based on microelectrochemistry, multiphase transport, and hydrodynamic flow confinement of liquids are presented.
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15
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Hydrodynamic Flow Confinement Technology in Microfluidic Perfusion Devices. MICROMACHINES 2012. [DOI: 10.3390/mi3020442] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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16
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Ainla A, Jeffries GDM, Brune R, Orwar O, Jesorka A. A multifunctional pipette. LAB ON A CHIP 2012; 12:1255-61. [PMID: 22252460 PMCID: PMC3803106 DOI: 10.1039/c2lc20906c] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Microfluidics has emerged as a powerful laboratory toolbox for biologists, allowing manipulation and analysis of processes at a cellular and sub-cellular level, through utilization of microfabricated features at size-scales relevant to that of a single cell. In the majority of microfluidic devices, sample processing and analysis occur within closed microchannels, imposing restrictions on sample preparation and use. We present an optimized non-contact open-volume microfluidic tool to overcome these and other restrictions, through the use of a hydrodynamically confined microflow pipette, serving as a multifunctional solution handling and dispensing tool. The geometries of the tool have been optimised for use in optical microscopy, with integrated solution reservoirs to reduce reagent use, contamination risks and cleaning requirements. Device performance was characterised using both epifluorescence and total internal reflection fluorescence (TIRF) microscopy, resulting in ~200 ms and ~130 ms exchange times at ~100 nm and ~30 μm distances to the surface respectively.
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Kaigala GV, Lovchik RD, Drechsler U, Delamarche E. A vertical microfluidic probe. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:5686-93. [PMID: 21476506 DOI: 10.1021/la2003639] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Performing localized chemical events on surfaces is critical for numerous applications. We earlier invented the microfluidic probe (MFP), which circumvented the need to process samples in closed microchannels by hydrodynamically confining liquids that performed chemistries on surfaces (Juncker et al. Nat. Mater. 2005, 4, 622-628). Here we present a new and versatile probe, the vertical MFP (vMFP), which operates in the scanning mode while overcoming earlier challenges that limited the practical implementation of the MFP technology. The key component of the vMFP is the head, a microfluidic device (∼1 cm(2) in area) consisting of glass and Si and having microfluidic features fabricated in-plane in the Si layer. The base configuration of the head has two micrometer-size channels that inject/aspirate liquids and terminate at the apex which is ∼1 mm(2). In scanning mode, the head is oriented vertically with the apex parallel to the surface with typical spacing of 1-30 μm. Such length scales and using flow rates from nanoliters/second to microliters/second allow chemical events to be performed on surfaces with tens of picoliter quantities of reagents. Before scanning, the head is clipped on a holder for leak-free, low dead volume interface assembly, providing a simple world-to-chip interface. Surfaces are scanned by mounting the holder on a computer-controlled stage having ∼0.1 μm resolution in positioning. We present detailed steps to fabricate vMFP heads having channels with dimensions from 1 μm × 1 μm to 50 μm × 50 μm for liquid localization over areas of 10-10,000 μm(2). Additionally, advanced design strategies are described to achieve high yield in fabrication and to support a broad range of applications. These include particulate filters, redundant aperture architectures, inclined flow-paths that service apertures, and multiple channels to enable symmetric flow confinement. We also present a method to characterize flow confinement and estimate the distance between the head and the surface by monitoring the evolution of a solution of fluorescently labeled antibody on an activated glass surface. This flow characterization reveals regimes of operation suitable for different surface topographies. We further integrate the dispensing of immersion liquid to the vMFP head for processing surfaces for extended periods of time (∼60 min). The versatility of the vMFP is exemplified by patterning fluorescently labeled proteins, inactivation of cells using sodium hypochlorite, and staining living NIH fibroblasts with Cellomics. These applications are enabled by the compact design of the head, which provides easy access to the surface, simplifies alignment, and enables processing surfaces having dimensions from the micrometer to the centimeter scale and with large topographical variations. We therefore believe that ease-of-operation, reconfigurability, and conservative use of chemicals by the vMFP will lead to its widespread use by microtechnologists and the chemical and biomedical communities.
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Affiliation(s)
- G V Kaigala
- IBM Research-Zurich, Säumerstrasse 4, CH-8803 Rüschlikon, Switzerland
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Christ KV, Turner KT. Design of hydrodynamically confined microfluidics: controlling flow envelope and pressure. LAB ON A CHIP 2011; 11:1491-1501. [PMID: 21359386 DOI: 10.1039/c0lc00416b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Closed-channel microfluidic devices are widely used in a number of chemical and biological applications; however, it is often difficult to interact with samples, such as cells, that are enclosed inside them. Hydrodynamically confined microflows (HCMs) allow microfluidic-type flows to be generated in open liquid environments, such as Petri dishes, thus greatly increasing the flexibility of microfluidic approaches. HCMs have previously been used for protein patterning and selective cell treatment applications, but the underlying fluid mechanics is not fully understood. Here, we examine the effect of device geometry and flow parameters on the properties of the flow envelope and pressure drop of several two-port HCM devices using a combination of experiments and modeling. A three-port device, which allows for different flow envelope shapes to be generated, is also analyzed. The experimental results agree well with the 3-D computational fluid dynamics simulations, with the majority of the measurements within 10% of the simulations. The results presented provide a framework for understanding the fluid mechanics of HCMs and will aid in the design of HCM devices for a broad range of applications.
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Affiliation(s)
- Kevin V Christ
- Department of Mechanical Engineering, University of Wisconsin, Madison, WI 53706, USA
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Perrault CM, Qasaimeh MA, Brastaviceanu T, Anderson K, Kabakibo Y, Juncker D. Integrated microfluidic probe station. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:115107. [PMID: 21133501 DOI: 10.1063/1.3497302] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The microfluidic probe (MFP) consists of a flat, blunt tip with two apertures for the injection and reaspiration of a microjet into a solution--thus hydrodynamically confining the microjet--and is operated atop an inverted microscope that enables live imaging. By scanning across a surface, the microjet can be used for surface processing with the capability of both depositing and removing material; as it operates under immersed conditions, sensitive biological materials and living cells can be processed. During scanning, the MFP is kept immobile and centered over the objective of the inverted microscope, a few micrometers above a substrate that is displaced by moving the microscope stage and that is flushed continuously with the microjet. For consistent and reproducible surface processing, the gap between the MFP and the substrate, the MFP's alignment, the scanning speed, the injection and aspiration flow rates, and the image capture need all to be controlled and synchronized. Here, we present an automated MFP station that integrates all of these functionalities and automates the key operational parameters. A custom software program is used to control an independent motorized Z stage for adjusting the gap, a motorized microscope stage for scanning the substrate, up to 16 syringe pumps for injecting and aspirating fluids, and an inverted fluorescence microscope equipped with a charge-coupled device camera. The parallelism between the MFP and the substrate is adjusted using manual goniometer at the beginning of the experiment. The alignment of the injection and aspiration apertures along the scanning axis is performed using a newly designed MFP screw holder. We illustrate the integrated MFP station by the programmed, automated patterning of fluorescently labeled biotin on a streptavidin-coated surface.
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Affiliation(s)
- C M Perrault
- Department of Biomedical Engineering, McGill University, Montréal, Quebec, H3A 1A4, Canada
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Shiku H, Yamakawa T, Nashimoto Y, Takahashi Y, Torisawa YS, Yasukawa T, Ito-Sasaki T, Yokoo M, Abe H, Kambara H, Matsue T. A microfluidic dual capillary probe to collect messenger RNA from adherent cells and spheroids. Anal Biochem 2009; 385:138-42. [DOI: 10.1016/j.ab.2008.10.039] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Revised: 10/28/2008] [Accepted: 10/28/2008] [Indexed: 10/21/2022]
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Abstract
Transcranial magnetic stimulation is a remarkable tool for neuroscience research, with a multitude of diagnostic and therapeutic applications. Surprisingly, application of the same magnetic stimulation directly to neurons that are dissected from the brain and grown in vitro was not reported to activate them to date. Here we report that central nervous system neurons patterned on large enough one-dimensional rings can be magnetically stimulated in vitro. In contrast, two-dimensional cultures with comparable size do not respond to excitation. This happens because the one-dimensional pattern enforces an ordering of the axons along the ring, which is designed to follow the lines of the magnetically induced electric field. A small group of sensitive (i.e., initiating) neurons respond even when the network is disconnected, and are presumed to excite the entire network when it is connected. This implies that morphological and electrophysiological properties of single neurons are crucial for magnetic stimulation. We conjecture that the existence of a select group of neurons with higher sensitivity may occur in the brain in vivo as well, with consequences for transcranial magnetic stimulation.
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Peng C, Palazzo RE, Wilke I. Laser intensity dependence of femtosecond near-infrared optoinjection. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:041903. [PMID: 17500917 DOI: 10.1103/physreve.75.041903] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Revised: 12/13/2006] [Indexed: 05/06/2023]
Abstract
We report an experimental study on transient membrane permeabilization of single living bovine aortic endothelial cells (BAEC) by tightly focused femtosecond near-infrared laser pulses. The membrane permeabilization of the BAEC cells was studied as a function of the incident laser intensity. The rate of dye uptake by the cells was analyzed using time-lapse imaging. We found that membrane permeabilization occurs for laser intensities higher than 4.0 x 10(12) W/cm(2). For laser intensity above 3.3 x 10(13) W/cm(2) the cell disintegrates. Within these two limits the rate of dye uptake increases logarithmically with increasing laser intensity. This functional dependence is explained by considering the Gaussian intensity distribution across the laser focal spot. Cell membrane permeabilization is explained by the creation of a plasma within the laser focal spot. The physical understanding of the relationship between dye uptake, pore characteristics, and laser intensity allows control of the concentrations of molecules delivered into cells through the control of pore characteristics.
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Affiliation(s)
- Cheng Peng
- Department of Physics, Applied Physics & Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA
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Jacobi S, Moses E. Variability and corresponding amplitude-velocity relation of activity propagating in one-dimensional neural cultures. J Neurophysiol 2007; 97:3597-606. [PMID: 17344374 DOI: 10.1152/jn.00608.2006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigate the propagation of neural activity along one-dimensional rat hippocampal cultures patterned in lines over multielectrode arrays. Activity occurs spontaneously or is evoked by local electrical or chemical stimuli, with different resulting propagation velocities and firing rate amplitudes. A variability of an order of magnitude in velocity and amplitude is observed in spontaneous activity. A linear relation between velocity and amplitude is identified. We define a measure for neuron activation synchrony and find that it correlates with front velocity and is higher for electrically evoked fronts. We present a model that explains the linear relation between amplitude and velocity, which highlights the role of synchrony. The relation to current models for signal propagation in neural media is discussed.
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Affiliation(s)
- Shimshon Jacobi
- Department of Physics of Complex Systems, The Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel.
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Feinerman O, Segal M, Moses E. Identification and dynamics of spontaneous burst initiation zones in unidimensional neuronal cultures. J Neurophysiol 2007; 97:2937-48. [PMID: 17287439 DOI: 10.1152/jn.00958.2006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Spontaneous activity is typical of in vitro neural networks, often in the form of large population bursts. The origins of this activity are attributed to intrinsically bursting neurons and to noisy backgrounds as well as to recurrent network connections. Spontaneous activity is often observed to emanate from localized sources or initiation zones, propagating from there to excite large populations of neurons. In this study, we use unidimensional cultures to overcome experimental difficulties in identifying initiation zones in vivo and in dissociated two-dimensional cultures. We found that spontaneous activity in these cultures is initiated exclusively in localized zones that are characterized by high neuronal density but also by recurrent and inhibitory network connections. We demonstrate that initiation zones compete in driving network activity in a winner-takes-most scenario.
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Affiliation(s)
- Ofer Feinerman
- Department of Physics of Complex Systems, The Weizmann Institute of Science, Rehovot, Israel.
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Klauke N, Smith GL, Cooper JM. Microfluidic Partitioning of the Extracellular Space around Single Cardiac Myocytes. Anal Chem 2007; 79:1205-12. [PMID: 17263355 DOI: 10.1021/ac061547k] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper describes the partitioning of the extracellular space around an electrically activated single cardiac myocyte, constrained within a microfluidic device. Central to this new method is the production of a hydrophobic gap-structure, which divides the extracellular space into two distinct microfluidic pools. The content of these pools was controlled using a pair of concentric automated pipets (subsequently called "dual superfusion pipet"), each providing the ability to dispense (i.e., the source, inner pipet) and aspirate (the sink, outer pipet) a buffer solution (perfusate) into each of the two pools. For rapid solution switching around the cell, additional dual superfusion pipets were inserted into the microchannel for defined time periods using a piezostepper, enabling us to add a test solution, such as a drug. Three distinct areas of the cell were manipulated, namely, the microfluidic environment, the cellular membrane, and the intracellular space. Planar integrated microelectrodes enabled the electrical stimulation of the cardiomyocyte and the recording of the evoked action potential. The device was mounted on an inverted microscope to allow simultaneous sarcomere length and epifluorescence measurements during evoked electrical activity, including, for example, the response of the stimulated end of the cardiac myocyte in comparison with the untreated cell end.
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Affiliation(s)
- Norbert Klauke
- Department of Electronics, University of Glasgow, Glasgow G12 8LT, Scotland.
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Abstracts of the 15th Annual Meeting of the Israel Society for Neuroscience (Eilat, Israel, December 3–5, 2006). Neural Plast 2007. [PMCID: PMC2377328 DOI: 10.1155/2007/73079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The Israel Society for Neuroscience (ISFN) was founded in 1993 by a group of Israeli leading scientists conducting research in the area of neurobiology. The primary goal of the society was to promote and disseminate the knowledge and understanding acquired by its members, and to strengthen interactions between them. Since then, the society holds its annual meeting every year in Eilat during the month of December. At these annual meetings the senior Israeli neurobiologists, their teams, and their graduate students, as well as foreign scientists and students, present their recent research findings in platform and poster presentations. The meeting also offers the opportunity for the researchers to exchange information with each other, often leading to the initiation of collaborative studies. Both the number of members of the society and of those participating in the annual meeting is constantly increasing, and it is anticipated that this year about 600 scientists will convene at the Princess Hotel in Eilat, Israel. Further information concerning the Israel Society for Neuroscience can be found at http://www.isfn.org.il. Committee: Zvi Wollberg (President) Tel Aviv University Edi Barkai University of Haifa Etti Grauer Israel Institute for Biological Research, Ness Ziona Yoram Rami Grossman Ben Gurion University of the Negev Yoel Yaari Hebrew University of Jerusalem Gal Yadid Bar-Ilan University Shlomo Rotshenker (President Elect) Hebrew University of Jerusalem Ettie Grauer (Treasurer) Israel Institute for Biological Research, Ness Ziona Michal Gilady (Administrator) Rishon Le Zion
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Feinerman O, Moses E. Transport of information along unidimensional layered networks of dissociated hippocampal neurons and implications for rate coding. J Neurosci 2006; 26:4526-34. [PMID: 16641232 PMCID: PMC6674052 DOI: 10.1523/jneurosci.4692-05.2006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The ability of synchronous population activity in layered networks to transmit a rate code is a focus of recent debate. We investigate these issues using a patterned unidimensional hippocampal culture. The network exhibits population bursts that travel its full length, with the advantage that signals propagate along a clearly defined path. The amplitudes of activity are measured using calcium imaging, a good approximate of population rate code, and the distortion of the signal as it travels is analyzed. We demonstrate that propagation along the line is precisely described by information theory as a chain of Gaussian communication channels. The balance of excitatory and inhibitory synapses is crucial for this transmission. However, amplitude information carried along this layered neuronal structure fails within 3 mm, approximately 10 mean axon lengths, and is limited by noise in the synaptic transmission. We conclude that rate codes cannot be reliably transmitted through long layered networks.
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Affiliation(s)
- Ofer Feinerman
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel.
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Juncker D, Schmid H, Delamarche E. Multipurpose microfluidic probe. NATURE MATERIALS 2005; 4:622-8. [PMID: 16041377 DOI: 10.1038/nmat1435] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2005] [Accepted: 05/20/2005] [Indexed: 05/03/2023]
Abstract
Microfluidic systems allow (bio)chemical processes to be miniaturized with the benefit of shorter time-to-result, parallelism, reduced sample consumption, laminar flow, and increased control and efficiency. However, such miniaturization inherently limits the size of the solid objects that can be processed and entails new challenges such as the interfacing of macroscopic samples with microscopic conduits. Here, we report a microfluidic probe (MFP) that overcomes these problems by combining the concepts of 'microfluidics' and of 'scanning probes'. Here, liquid boundaries formed by hydrodynamic forces underneath the MFP confine a flow of processing solution and replace the solid walls of closed microchannels. The MFP is therefore mobile and can be used to process large surfaces and objects by scanning across them. We illustrate the versatility of this concept with several examples including protein microarraying, complex gradient-formation, multiphase laminar-flow patterning, erasing, localized staining of cells and the contact-free detachment of a single cell. Many constraints imposed by the monolithic construction of microfluidic channels can now be circumvented using an MFP, opening up new avenues for microfluidic processing.
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Affiliation(s)
- David Juncker
- Zürich Research laboratory, IBM Research GmbH, Rüschlikon, Switzerland.
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Feinerman O, Segal M, Moses E. Signal propagation along unidimensional neuronal networks. J Neurophysiol 2005; 94:3406-16. [PMID: 16049148 DOI: 10.1152/jn.00264.2005] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Dissociated neurons were cultured on lines of various lengths covered with adhesive material to obtain an experimental model system of linear signal transmission. The neuronal connectivity in the linear culture is characterized, and it is demonstrated that local spiking activity is relayed by synaptic transmission along the line of neurons to develop into a large-scale population burst. Formally, this can be treated as a one-dimensional information channel. Directional propagation of both spontaneous and stimulated bursts along the line, imaged with the calcium indicator Fluo-4, revealed the existence of two different propagation velocities. Initially, a small number of neighboring neurons fire, leading to a slow, small and presumably asynchronous wave of activity. The signal then spontaneously develops to encompass much larger and further populations, and is characterized by fast propagation of high-amplitude activity, which is presumed to be synchronous. These results are well described by an existing theoretical framework for propagation based on an integrate-and-fire model.
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Affiliation(s)
- Ofer Feinerman
- Department of Physics of Complex Systems, The Weizmann Institute of Science, Rehovot, Israel 76100.
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