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Jameson AT, Spera LK, Nguyen DL, Paul EM, Tabuchi M. Membrane-coated glass electrodes for stable, low-noise electrophysiology recordings in Drosophila central neurons. J Neurosci Methods 2024; 404:110079. [PMID: 38340901 PMCID: PMC11034715 DOI: 10.1016/j.jneumeth.2024.110079] [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: 11/20/2023] [Revised: 01/21/2024] [Accepted: 02/06/2024] [Indexed: 02/12/2024]
Abstract
BACKGROUND Electrophysiological recording with glass electrodes is one of the best techniques to measure membrane potential dynamics and ionic currents of voltage-gated channels in neurons. However, artifactual variability of the biophysical state variables that determine recording quality can be caused by insufficient affinity between the electrode and cell membrane during the recording. NEW METHOD We introduce a phospholipid membrane coating on glass electrodes to improve intracellular electrophysiology recording quality. Membrane-coated electrodes were prepared with a tip-dip protocol for perforated-patch, sharp-electrode current-clamp, and cell-attached patch-clamp recordings from specific circadian clock neurons in Drosophila. We perform quantitative comparisons based on the variability of functional biophysical parameters used in various electrophysiological methods, and advanced statistical comparisons based on the degree of stationariness and signal-to-noise ratio. RESULTS Results indicate a dramatic reduction in artifactual variabilities of functional parameters from enhanced stability. We also identify significant exclusions of a statistically estimated noise component in a time series of membrane voltage signals, improving signal-to-noise ratio. COMPARISON WITH EXISTING METHODS Compared to standard glass electrodes, using membrane-coated glass electrodes achieves improved recording quality in intracellular electrophysiology. CONCLUSIONS Electrophysiological recordings from Drosophila central neurons can be technically challenging, however, membrane-coated electrodes will possibly be beneficial for reliable data acquisition and improving the technical feasibility of axonal intracellular activities measurements and single-channel recordings. The improved electrical stability of the recordings should also contribute to increased mechanical stability, thus facilitating long-term stable measurements of neural activity. Therefore, it is possible that membrane-coated electrodes will be useful for any model system.
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Affiliation(s)
- Angelica T Jameson
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Lucia K Spera
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Dieu Linh Nguyen
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Elizabeth M Paul
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Masashi Tabuchi
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, United States.
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2
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Sharon A, Shmoel N, Erez H, Jankowski MM, Friedmann Y, Spira ME. Ultrastructural Analysis of Neuroimplant-Parenchyma Interfaces Uncover Remarkable Neuroregeneration Along-With Barriers That Limit the Implant Electrophysiological Functions. Front Neurosci 2021; 15:764448. [PMID: 34880722 PMCID: PMC8645653 DOI: 10.3389/fnins.2021.764448] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/21/2021] [Indexed: 12/13/2022] Open
Abstract
Despite increasing use of in vivo multielectrode array (MEA) implants for basic research and medical applications, the critical structural interfaces formed between the implants and the brain parenchyma, remain elusive. Prevailing view assumes that formation of multicellular inflammatory encapsulating-scar around the implants [the foreign body response (FBR)] degrades the implant electrophysiological functions. Using gold mushroom shaped microelectrodes (gMμEs) based perforated polyimide MEA platforms (PPMPs) that in contrast to standard probes can be thin sectioned along with the interfacing parenchyma; we examined here for the first time the interfaces formed between brains parenchyma and implanted 3D vertical microelectrode platforms at the ultrastructural level. Our study demonstrates remarkable regenerative processes including neuritogenesis, axon myelination, synapse formation and capillaries regrowth in contact and around the implant. In parallel, we document that individual microglia adhere tightly and engulf the gMμEs. Modeling of the formed microglia-electrode junctions suggest that this configuration suffice to account for the low and deteriorating recording qualities of in vivo MEA implants. These observations help define the anticipated hurdles to adapting the advantageous 3D in vitro vertical-electrode technologies to in vivo settings, and suggest that improving the recording qualities and durability of planar or 3D in vivo electrode implants will require developing approaches to eliminate the insulating microglia junctions.
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Affiliation(s)
- Aviv Sharon
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Nava Shmoel
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Harvey M. Kruger Family Center for Nanoscience, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Hadas Erez
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Maciej M. Jankowski
- The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel
- Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yael Friedmann
- Bio-Imaging Unit, The Alexander Silberman Institute of Life Science the Hebrew University of Jerusalem, Jerusalem, Israel
| | - Micha E. Spira
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Charles E. Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Harvey M. Kruger Family Center for Nanoscience, The Hebrew University of Jerusalem, Jerusalem, Israel
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3
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Gwon HJ, Lim D, Ahn HS. Bioanalytical chemistry with scanning electrochemical microscopy. B KOREAN CHEM SOC 2021. [DOI: 10.1002/bkcs.12383] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Hyo Jin Gwon
- Department of Chemistry Institution: Yonsei University Seoul South Korea
| | - Donghoon Lim
- Department of Chemistry Institution: Yonsei University Seoul South Korea
| | - Hyun S. Ahn
- Department of Chemistry Institution: Yonsei University Seoul South Korea
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4
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Gao J, Liao C, Liu S, Xia T, Jiang G. Nanotechnology: new opportunities for the development of patch-clamps. J Nanobiotechnology 2021; 19:97. [PMID: 33794903 PMCID: PMC8017657 DOI: 10.1186/s12951-021-00841-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/23/2021] [Indexed: 12/29/2022] Open
Abstract
The patch-clamp technique is one of the best approaches to investigate neural excitability. Impressive improvements towards the automation of the patch-clamp technique have been made, but obvious limitations and hurdles still exist, such as parallelization, volume displacement in vivo, and long-term recording. Nanotechnologies have provided opportunities to overcome these hurdles by applying electrical devices on the nanoscale. Electrodes based on nanowires, nanotubes, and nanoscale field-effect transistors (FETs) are confirmed to be robust and less invasive tools for intracellular electrophysiological recording. Research on the interface between the nanoelectrode and cell membrane aims to reduce the seal conductance and further improve the recording quality. Many novel recording approaches advance the parallelization, and precision with reduced invasiveness, thus improving the overall intracellular recording system. The combination of nanotechnology and the present intracellular recording framework is a revolutionary and promising orientation, potentially becoming the next generation electrophysiological recording technique and replacing the conventional patch-clamp technique. Here, this paper reviews the recent advances in intracellular electrophysiological recording techniques using nanotechnology, focusing on the design of noninvasive and greatly parallelized recording systems based on nanoelectronics.
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Affiliation(s)
- Jia Gao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chunyang Liao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China. .,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Sijin Liu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Tian Xia
- Division of NanoMedicine, Department of Medicine, University of California, Los Angeles, CA, 90095, USA
| | - Guibin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China
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5
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Scheibel OV, Schrlau MG. A Self‐contained Two‐electrode Nanosensor for Electrochemical Analysis in Aqueous Microenvironments. ELECTROANAL 2020. [DOI: 10.1002/elan.201900672] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Olivia V. Scheibel
- Department of Mechanical Engineering Rochester Institute of Technology 1 Lomb Memorial Drive Rochester New York 14425 USA
| | - Michael G. Schrlau
- Department of Mechanical Engineering Rochester Institute of Technology 1 Lomb Memorial Drive Rochester New York 14425 USA
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Kumar SS, Baker MS, Okandan M, Muthuswamy J. Engineering microscale systems for fully autonomous intracellular neural interfaces. MICROSYSTEMS & NANOENGINEERING 2020; 6:1. [PMID: 34567658 PMCID: PMC8433365 DOI: 10.1038/s41378-019-0121-y] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 05/08/2023]
Abstract
Conventional electrodes and associated positioning systems for intracellular recording from single neurons in vitro and in vivo are large and bulky, which has largely limited their scalability. Further, acquiring successful intracellular recordings is very tedious, requiring a high degree of skill not readily achieved in a typical laboratory. We report here a robotic, MEMS-based intracellular recording system to overcome the above limitations associated with form factor, scalability, and highly skilled and tedious manual operations required for intracellular recordings. This system combines three distinct technologies: (1) novel microscale, glass-polysilicon penetrating electrode for intracellular recording; (2) electrothermal microactuators for precise microscale movement of each electrode; and (3) closed-loop control algorithm for autonomous positioning of electrode inside single neurons. Here we demonstrate the novel, fully integrated system of glass-polysilicon microelectrode, microscale actuators, and controller for autonomous intracellular recordings from single neurons in the abdominal ganglion of Aplysia californica (n = 5 cells). Consistent resting potentials (<-35 mV) and action potentials (>60 mV) were recorded after each successful penetration attempt with the controller and microactuated glass-polysilicon microelectrodes. The success rate of penetration and quality of intracellular recordings achieved using electrothermal microactuators were comparable to that of conventional positioning systems. Preliminary data from in vivo experiments in anesthetized rats show successful intracellular recordings. The MEMS-based system offers significant advantages: (1) reduction in overall size for potential use in behaving animals, (2) scalable approach to potentially realize multi-channel recordings, and (3) a viable method to fully automate measurement of intracellular recordings. This system will be evaluated in vivo in future rodent studies.
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Affiliation(s)
- Swathy Sampath Kumar
- Biomedical Engineering, School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ 85287 USA
| | - Michael S. Baker
- Mechanical Engineering, Sandia National laboratories, Albuquerque, NM USA
| | | | - Jit Muthuswamy
- Biomedical Engineering, School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ 85287 USA
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7
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Jayant K, Wenzel M, Bando Y, Hamm JP, Mandriota N, Rabinowitz JH, Plante IJL, Owen JS, Sahin O, Shepard KL, Yuste R. Flexible Nanopipettes for Minimally Invasive Intracellular Electrophysiology In Vivo. Cell Rep 2019; 26:266-278.e5. [PMID: 30605681 PMCID: PMC7263204 DOI: 10.1016/j.celrep.2018.12.019] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 10/23/2018] [Accepted: 12/04/2018] [Indexed: 12/01/2022] Open
Abstract
Intracellular recordings in vivo remains the best technique to link single-neuron electrical properties to network function. Yet existing methods are limited in accuracy, throughput, and duration, primarily via washout, membrane damage, and movement-induced failure. Here, we introduce flexible quartz nanopipettes (inner diameters of 10-25 nm and spring constant of ∼0.08 N/m) as nanoscale analogs of traditional glass microelectrodes. Nanopipettes enable stable intracellular recordings (seal resistances of 500 to ∼800 MΩ, 5 to ∼10 cells/nanopipette, and duration of ∼1 hr) in anaesthetized and awake head-restrained mice, exhibit minimal diffusional flux, and facilitate precise recording and stimulation. When combined with quantum-dot labels and microprisms, nanopipettes enable two-photon targeted electrophysiology from both somata and dendrites, and even paired recordings from neighboring neurons, while permitting simultaneous population imaging across cortical layers. We demonstrate the versatility of this method by recording from parvalbumin-positive (Pv) interneurons while imaging seizure propagation, and we find that Pv depolarization block coincides with epileptic spread. Flexible nanopipettes present a simple method to procure stable intracellular recordings in vivo.
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Affiliation(s)
- Krishna Jayant
- Department of Electrical Engineering, Columbia University, New York, NY 10027, USA; Department of Biological Sciences, Columbia University, New York, NY 10027, USA; NeuroTechnology Center, Columbia University, New York, NY 10027, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA.
| | - Michael Wenzel
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA; NeuroTechnology Center, Columbia University, New York, NY 10027, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Yuki Bando
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA; NeuroTechnology Center, Columbia University, New York, NY 10027, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Jordan P Hamm
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA; NeuroTechnology Center, Columbia University, New York, NY 10027, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Nicola Mandriota
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Jake H Rabinowitz
- Department of Electrical Engineering, Columbia University, New York, NY 10027, USA
| | - Ilan Jen-La Plante
- Department of Chemistry, Columbia University, New York, NY 10027, USA; NeuroTechnology Center, Columbia University, New York, NY 10027, USA
| | - Jonathan S Owen
- Department of Chemistry, Columbia University, New York, NY 10027, USA; NeuroTechnology Center, Columbia University, New York, NY 10027, USA
| | - Ozgur Sahin
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA; Department of Physics, Columbia University, New York, NY 10027, USA; NeuroTechnology Center, Columbia University, New York, NY 10027, USA
| | - Kenneth L Shepard
- Department of Electrical Engineering, Columbia University, New York, NY 10027, USA; Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA; NeuroTechnology Center, Columbia University, New York, NY 10027, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Rafael Yuste
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA; NeuroTechnology Center, Columbia University, New York, NY 10027, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
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8
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9
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Matlab software for impedance spectroscopy designed for neuroscience applications. J Neurosci Methods 2018; 307:70-83. [PMID: 29964081 DOI: 10.1016/j.jneumeth.2018.06.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 06/25/2018] [Accepted: 06/25/2018] [Indexed: 11/24/2022]
Abstract
BACKGROUND Metal electrodes are a mainstay of neuroscience. Characterization of the electrical impedance properties of these cuffs is important to ensure successful and repeatable fabrication, achieve a target impedance, revise novel designs, and quantify the success or failure of implantation and any potential subsequent damage or encapsulation by scar tissue. NEW METHODS Impedances are frequently characterized using lumped-parameter circuit models of the electrode-electrolyte interface. Open-source tools to gather and analyze these frequency sweep data are lacking. Here, we present such software, in the form of Matlab code, which includes a GUI. It automatically acquires frequency sweep data and subsequently fits a simplified Randles model to these data, over a user specified frequency range, providing the user with the model parameter estimates. Also, it can measure an unknown impedance of an element over a range of frequencies, as long as an external resistor can be added for the measurements. RESULTS The tool was tested on five bright platinum nerve cuffs in vitro. The average charge transfer resistance, solution resistance, CPE value, and impedance magnitude were estimated. COMPARISON TO EXISTING METHODS The measured values of the impedance of cuffs were in agreement with the literature (Wei and Grill, 2009). Variation between cuffs fabricated as consistently as possible amounted to 10% for impedance magnitude and 4° for impedance phase. CONCLUSION The results show that this low-cost tool can be used to characterize a cuff across different conditions including after implantation. The latter makes it useful for a longer-term study of electrode viability.
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10
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Spira ME, Shmoel N, Huang SHM, Erez H. Multisite Attenuated Intracellular Recordings by Extracellular Multielectrode Arrays, a Perspective. Front Neurosci 2018; 12:212. [PMID: 29692701 PMCID: PMC5902558 DOI: 10.3389/fnins.2018.00212] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Accepted: 03/16/2018] [Indexed: 11/13/2022] Open
Abstract
Multielectrode arrays (MEA) are used extensively for basic and applied electrophysiological research of neuronal- and cardiomyocyte-networks. Whereas immense progress has been made in realizing sophisticated MEA platforms of thousands of addressable, high-density, small diameter, low impedance sensors, the quality of the interfaces formed between excitable cells and classical planar sensor has not improved. As a consequence in vitro and in vivo MEA are “blind” to the rich and important “landscape” of sub-threshold synaptic potentials generated by individual neurons. Disregarding this essential fraction of network signaling repertoire has become the standard and almost the “scientific ideology” of MEA users. To overcome the inherent limitations of substrate integrated planar MEA platforms that only record extracellular field potentials, a number of laboratories have developed in vitro MEA for intracellular recordings. Most of these novel devices use vertical nano-rods or nano-wires that penetrate the plasma membrane of cultured cells and record the electrophysiological signaling in a manner similar to sharp intracellular microelectrodes. In parallel, our laboratory began to develop a bioinspired approach in-which cell biological energy resources are harnessed to self-force a cell into intimate contact with extracellular gold mushroom-shaped microelectrodes to record attenuated synaptic- and action-potentials with characteristic features of intracellular recordings. Here we describe some of the experiments that helped evolve the approach and elaborate on the biophysical principles that make it possible to record intracellular potentials by an array of extracellular electrode. We illustrate the qualities and limitations of the method and discuss prospects for further improvement of this technology.
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Affiliation(s)
- Micha E Spira
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Charles E Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Harvey M. Kruger Family Center for Nanoscience, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Nava Shmoel
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Charles E Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Harvey M. Kruger Family Center for Nanoscience, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Shun-Ho M Huang
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Charles E Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Harvey M. Kruger Family Center for Nanoscience, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Hadas Erez
- Department of Neurobiology, The Alexander Silberman Institute of Life Science, The Charles E Smith Family and Prof. Joel Elkes Laboratory for Collaborative Research in Psychobiology, The Harvey M. Kruger Family Center for Nanoscience, Hebrew University of Jerusalem, Jerusalem, Israel
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11
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Affiliation(s)
- Ede A Rancz
- Cortical Circuits Laboratory, Francis Crick Institute, London, UK
| | - Andreas T Schaefer
- Neurophysiology of Behaviour Laboratory, Francis Crick Institute, London, UK, and the Department of Neuroscience, Physiology & Pharmacology, University College London, London, UK
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12
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Abstract
Nanoneedles are high aspect ratio nanostructures with a unique biointerface. Thanks to their peculiar yet poorly understood interaction with cells, they very effectively sense intracellular conditions, typically with lower toxicity and perturbation than traditionally available probes. Through long-term, reversible interfacing with cells, nanoneedles can monitor biological functions over the course of several days. Their nanoscale dimension and the assembly into large-scale, ordered, dense arrays enable monitoring the functions of large cell populations, to provide functional maps with submicron spatial resolution. Intracellularly, they sense electrical activity of complex excitable networks, as well as concentration, function, and interaction of biomolecules in situ, while extracellularly they can measure the forces exerted by cells with piconewton detection limits, or efficiently sort rare cells based on their membrane receptors. Nanoneedles can investigate the function of many biological systems, ranging from cells, to biological fluids, to tissues and living organisms. This review examines the devices, strategies, and workflows developed to use nanoneedles for sensing in biological systems.
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Affiliation(s)
- Ciro Chiappini
- Centre for Craniofacial and Regenerative Biology, King's College London , SE1 9RT, London, United Kingdom
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13
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Jayant K, Hirtz JJ, Plante IJL, Tsai DM, De Boer WDAM, Semonche A, Peterka DS, Owen JS, Sahin O, Shepard KL, Yuste R. Targeted intracellular voltage recordings from dendritic spines using quantum-dot-coated nanopipettes. NATURE NANOTECHNOLOGY 2017; 12:335-342. [PMID: 27941898 PMCID: PMC5901699 DOI: 10.1038/nnano.2016.268] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 11/02/2016] [Indexed: 05/21/2023]
Abstract
Dendritic spines are the primary site of excitatory synaptic input onto neurons, and are biochemically isolated from the parent dendritic shaft by their thin neck. However, due to the lack of direct electrical recordings from spines, the influence that the neck resistance has on synaptic transmission, and the extent to which spines compartmentalize voltage, specifically excitatory postsynaptic potentials, albeit critical, remains controversial. Here, we use quantum-dot-coated nanopipette electrodes (tip diameters ∼15-30 nm) to establish the first intracellular recordings from targeted spine heads under two-photon visualization. Using simultaneous somato-spine electrical recordings, we find that back propagating action potentials fully invade spines, that excitatory postsynaptic potentials are large in the spine head (mean 26 mV) but are strongly attenuated at the soma (0.5-1 mV) and that the estimated neck resistance (mean 420 MΩ) is large enough to generate significant voltage compartmentalization. Nanopipettes can thus be used to electrically probe biological nanostructures.
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Affiliation(s)
- Krishna Jayant
- Department of Electrical Engineering, Columbia University, New York, New York 10027, USA
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
- NeuroTechnology Center, Columbia University, New York, New York 10027, USA
- Kavli Institute of Brain Science, Columbia University, New York, New York 10027, USA
- Correspondence and requests for materials should be addressed to K.J.,
| | - Jan J. Hirtz
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
- NeuroTechnology Center, Columbia University, New York, New York 10027, USA
- Kavli Institute of Brain Science, Columbia University, New York, New York 10027, USA
| | - Ilan Jen-La Plante
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - David M. Tsai
- Department of Electrical Engineering, Columbia University, New York, New York 10027, USA
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
- NeuroTechnology Center, Columbia University, New York, New York 10027, USA
- Kavli Institute of Brain Science, Columbia University, New York, New York 10027, USA
| | - Wieteke D. A. M. De Boer
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
- NeuroTechnology Center, Columbia University, New York, New York 10027, USA
- Kavli Institute of Brain Science, Columbia University, New York, New York 10027, USA
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Alexa Semonche
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Darcy S. Peterka
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
- NeuroTechnology Center, Columbia University, New York, New York 10027, USA
- Kavli Institute of Brain Science, Columbia University, New York, New York 10027, USA
| | - Jonathan S. Owen
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Ozgur Sahin
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
- NeuroTechnology Center, Columbia University, New York, New York 10027, USA
| | - Kenneth L. Shepard
- Department of Electrical Engineering, Columbia University, New York, New York 10027, USA
- NeuroTechnology Center, Columbia University, New York, New York 10027, USA
- Kavli Institute of Brain Science, Columbia University, New York, New York 10027, USA
- Department of Biomedical Engineering, New York, New York 10027, USA
| | - Rafael Yuste
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
- NeuroTechnology Center, Columbia University, New York, New York 10027, USA
- Kavli Institute of Brain Science, Columbia University, New York, New York 10027, USA
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Fan Y, Han C, Zhang B. Recent advances in the development and application of nanoelectrodes. Analyst 2016; 141:5474-87. [PMID: 27510555 DOI: 10.1039/c6an01285j] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Nanoelectrodes have key advantages compared to electrodes of conventional size and are the tool of choice for numerous applications in both fundamental electrochemistry research and bioelectrochemical analysis. This Minireview summarizes recent advances in the development, characterization, and use of nanoelectrodes in nanoscale electroanalytical chemistry. Methods of nanoelectrode preparation include laser-pulled glass-sealed metal nanoelectrodes, mass-produced nanoelectrodes, carbon nanotube based and carbon-filled nanopipettes, and tunneling nanoelectrodes. Several new topics of their recent application are covered, which include the use of nanoelectrodes for electrochemical imaging at ultrahigh spatial resolution, imaging with nanoelectrodes and nanopipettes, electrochemical analysis of single cells, single enzymes, and single nanoparticles, and the use of nanoelectrodes to understand single nanobubbles.
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Affiliation(s)
- Yunshan Fan
- Department of Chemistry, University of Washington, Seattle, Washington 98115, USA.
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15
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Multisite electrophysiological recordings by self-assembled loose-patch-like junctions between cultured hippocampal neurons and mushroom-shaped microelectrodes. Sci Rep 2016; 6:27110. [PMID: 27256971 PMCID: PMC4891817 DOI: 10.1038/srep27110] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 05/12/2016] [Indexed: 11/25/2022] Open
Abstract
Substrate integrated planar microelectrode arrays is the “gold standard” method for millisecond-resolution, long-term, large-scale, cell-noninvasive electrophysiological recordings from mammalian neuronal networks. Nevertheless, these devices suffer from drawbacks that are solved by spike-detecting, spike-sorting and signal-averaging techniques which rely on estimated parameters that require user supervision to correct errors, merge clusters and remove outliers. Here we show that primary rat hippocampal neurons grown on micrometer sized gold mushroom-shaped microelectrodes (gMμE) functionalized simply by poly-ethylene-imine/laminin undergo self-assembly processes to form loose patch-like hybrid structures. More than 90% of the hybrids formed in this way record monophasic positive action potentials (APs). Of these, 34.5% record APs with amplitudes above 300 μV and up to 5,085 μV. This self-assembled neuron-gMμE configuration improves the recording quality as compared to planar MEA. This study characterizes and analyzes the electrophysiological signaling repertoire generated by the neurons-gMμE configuration, and discusses prospects to further improve the technology.
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Nanoelectrodes: Applications in electrocatalysis, single-cell analysis and high-resolution electrochemical imaging. Trends Analyt Chem 2016. [DOI: 10.1016/j.trac.2016.01.018] [Citation(s) in RCA: 126] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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A feasibility study of multi-site,intracellular recordings from mammalian neurons by extracellular gold mushroom-shaped microelectrodes. Sci Rep 2015; 5:14100. [PMID: 26365404 PMCID: PMC4568476 DOI: 10.1038/srep14100] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 08/18/2015] [Indexed: 01/20/2023] Open
Abstract
The development of multi-electrode array platforms for large scale recording of neurons is at the forefront of neuro-engineering research efforts. Recently we demonstrated, at the proof-of-concept level, a breakthrough neuron-microelectrode interface in which cultured Aplysia neurons tightly engulf gold mushroom-shaped microelectrodes (gMμEs). While maintaining their extracellular position, the gMμEs record synaptic- and action-potentials with characteristic features of intracellular recordings. Here we examined the feasibility of using gMμEs for intracellular recordings from mammalian neurons. To that end we experimentally examined the innate size limits of cultured rat hippocampal neurons to engulf gMμEs and measured the width of the “extracellular” cleft formed between the neurons and the gold surface. Using the experimental results we next analyzed the expected range of gMμEs-neuron electrical coupling coefficients. We estimated that sufficient electrical coupling levels to record attenuated synaptic- and action-potentials can be reached using the gMμE-neuron configuration. The definition of the engulfment limits of the gMμEs caps diameter at ≤2–2.5 μm and the estimated electrical coupling coefficients from the simulations pave the way for rational development and application of the gMμE based concept for in-cell recordings from mammalian neurons.
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Angle MR, Wang A, Thomas A, Schaefer AT, Melosh NA. Penetration of cell membranes and synthetic lipid bilayers by nanoprobes. Biophys J 2015; 107:2091-100. [PMID: 25418094 DOI: 10.1016/j.bpj.2014.09.023] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/08/2014] [Accepted: 09/16/2014] [Indexed: 11/28/2022] Open
Abstract
Nanoscale devices have been proposed as tools for measuring and controlling intracellular activity by providing electrical and/or chemical access to the cytosol. Unfortunately, nanostructures with diameters of 50-500 nm do not readily penetrate the cell membrane, and rationally optimizing nanoprobes for cell penetration requires real-time characterization methods that are capable of following the process of membrane penetration with nanometer resolution. Although extensive work has examined the rupture of supported synthetic lipid bilayers, little is known about the applicability of these model systems to living cell membranes with complex lipid compositions, cytoskeletal attachment, and membrane proteins. Here, we describe atomic force microscopy (AFM) membrane penetration experiments in two parallel systems: live HEK293 cells and stacks of synthetic lipid bilayers. By using the same probes in both systems, we were able to clearly identify membrane penetration in synthetic bilayers and compare these events with putative membrane penetration events in cells. We examined membrane penetration forces for three tip geometries and 18 chemical modifications of the probe surface, and in all cases the median forces required to penetrate cellular and synthetic lipid bilayers with nanoprobes were greater than 1 nN. The penetration force was sensitive to the probe's sharpness, but not its surface chemistry, and the force did not depend on cell surface or cytoskeletal properties, with cells and lipid stacks yielding similar forces. This systematic assessment of penetration under various mechanical and chemical conditions provides insights into nanoprobe-cell interactions and informs the design of future intracellular nanoprobes.
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Affiliation(s)
- Matthew R Angle
- Department of Materials Science and Engineering, Stanford University, Stanford, California
| | - Andrew Wang
- Department of Materials Science and Engineering, Stanford University, Stanford, California
| | - Aman Thomas
- Department of Materials Science and Engineering, Stanford University, Stanford, California
| | - Andreas T Schaefer
- Department of Materials Science and Engineering, Stanford University, Stanford, California
| | - Nicholas A Melosh
- Department of Materials Science and Engineering, Stanford University, Stanford, California.
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Angle MR, Cui B, Melosh NA. Nanotechnology and neurophysiology. Curr Opin Neurobiol 2015; 32:132-40. [PMID: 25889532 DOI: 10.1016/j.conb.2015.03.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 02/11/2015] [Accepted: 03/23/2015] [Indexed: 02/09/2023]
Abstract
Neuroscience would be revolutionized by a technique to measure intracellular electrical potentials that would not disrupt cellular physiology and could be massively parallelized. Though such a technology does not yet exist, the technical hurdles for fabricating minimally disruptive, solid-state electrical probes have arguably been overcome in the field of nanotechnology. Nanoscale devices can be patterned with features on the same length scale as biological components, and several groups have demonstrated that nanoscale electrical probes can measure the transmembrane potential of electrogenic cells. Developing these nascent technologies into robust intracellular recording tools will now require a better understanding of device-cell interactions, especially the membrane-inorganic interface. Here we review the state-of-the art in nanobioelectronics, emphasizing the characterization and design of stable interfaces between nanoscale devices and cells.
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Affiliation(s)
- Matthew R Angle
- Department of Materials Science and Engineering, Stanford University, CA, USA
| | - Bianxiao Cui
- Department of Chemistry, Stanford University, CA, USA
| | - Nicholas A Melosh
- Department of Materials Science and Engineering, Stanford University, CA, USA; Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
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Ajetunmobi A, Prina-Mello A, Volkov Y, Corvin A, Tropea D. Nanotechnologies for the study of the central nervous system. Prog Neurobiol 2014; 123:18-36. [PMID: 25291406 DOI: 10.1016/j.pneurobio.2014.09.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 09/29/2014] [Accepted: 09/29/2014] [Indexed: 12/16/2022]
Abstract
The impact of central nervous system (CNS) disorders on the human population is significant, contributing almost €800 billion in annual European healthcare costs. These disorders not only have a disabling social impact but also a crippling economic drain on resources. Developing novel therapeutic strategies for these disorders requires a better understanding of events that underlie mechanisms of neural circuit physiology. Studying the relationship between genetic expression, synapse development and circuit physiology in CNS function is a challenging task, involving simultaneous analysis of multiple parameters and the convergence of several disciplines and technological approaches. However, current gold-standard techniques used to study the CNS have limitations that pose unique challenges to furthering our understanding of functional CNS development. The recent advancement in nanotechnologies for biomedical applications has seen the emergence of nanoscience as a key enabling technology for delivering a translational bridge between basic and clinical research. In particular, the development of neuroimaging and electrophysiology tools to identify the aetiology and progression of CNS disorders have led to new insights in our understanding of CNS physiology and the development of novel diagnostic modalities for therapeutic intervention. This review focuses on the latest applications of these nanotechnologies for investigating CNS function and the improved diagnosis of CNS disorders.
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Affiliation(s)
- A Ajetunmobi
- Department of Clinical Medicine, Institute of Molecular Medicine, St. James' Hospital, Trinity College Dublin, Ireland; Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Ireland
| | - A Prina-Mello
- Department of Clinical Medicine, Institute of Molecular Medicine, St. James' Hospital, Trinity College Dublin, Ireland; Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Ireland.
| | - Y Volkov
- Department of Clinical Medicine, Institute of Molecular Medicine, St. James' Hospital, Trinity College Dublin, Ireland; Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Ireland
| | - A Corvin
- Department of Psychiatry, Institute of Molecular Medicine, St. James' Hospital, Trinity College Dublin, Ireland
| | - D Tropea
- Department of Psychiatry, Institute of Molecular Medicine, St. James' Hospital, Trinity College Dublin, Ireland.
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Insulated conducting cantilevered nanotips and two-chamber recording system for high resolution ion sensing AFM. Sci Rep 2014; 4:4454. [PMID: 24663394 PMCID: PMC3964513 DOI: 10.1038/srep04454] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 03/04/2014] [Indexed: 11/08/2022] Open
Abstract
Biological membranes contain ion channels, which are nanoscale pores allowing controlled ionic transport and mediating key biological functions underlying normal/abnormal living. Synthetic membranes with defined pores are being developed to control various processes, including filtration of pollutants, charge transport for energy storage, and separation of fluids and molecules. Although ionic transport (currents) can be measured with single channel resolution, imaging their structure and ionic currents simultaneously is difficult. Atomic force microscopy enables high resolution imaging of nanoscale structures and can be modified to measure ionic currents simultaneously. Moreover, the ionic currents can also be used to image structures. A simple method for fabricating conducting AFM cantilevers to image pore structures at high resolution is reported. Tungsten microwires with nanoscale tips are insulated except at the apex. This allows simultaneous imaging via cantilever deflections in normal AFM force feedback mode as well as measuring localized ionic currents. These novel probes measure ionic currents as small as picoampere while providing nanoscale spatial resolution surface topography and is suitable for measuring ionic currents and conductance of biological ion channels.
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Actis P, Tokar S, Clausmeyer J, Babakinejad B, Mikhaleva S, Cornut R, Takahashi Y, López Córdoba A, Novak P, Shevchuck AI, Dougan JA, Kazarian SG, Gorelkin PV, Erofeev AS, Yaminsky IV, Unwin PR, Schuhmann W, Klenerman D, Rusakov DA, Sviderskaya EV, Korchev YE. Electrochemical nanoprobes for single-cell analysis. ACS NANO 2014; 8:875-84. [PMID: 24377306 DOI: 10.1021/nn405612q] [Citation(s) in RCA: 156] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The measurement of key molecules in individual cells with minimal disruption to the biological milieu is the next frontier in single-cell analyses. Nanoscale devices are ideal analytical tools because of their small size and their potential for high spatial and temporal resolution recordings. Here, we report the fabrication of disk-shaped carbon nanoelectrodes whose radius can be precisely tuned within the range 5-200 nm. The functionalization of the nanoelectrode with platinum allowed the monitoring of oxygen consumption outside and inside a brain slice. Furthermore, we show that nanoelectrodes of this type can be used to impale individual cells to perform electrochemical measurements within the cell with minimal disruption to cell function. These nanoelectrodes can be fabricated combined with scanning ion conductance microscopy probes, which should allow high resolution electrochemical mapping of species on or in living cells.
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Affiliation(s)
- Paolo Actis
- Department of Medicine, Imperial College London , London W12 0NN, United Kingdom
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Cell adhesion promotion strategies for signal transduction enhancement in microelectrode array in vitro electrophysiology: An introductory overview and critical discussion. Curr Opin Colloid Interface Sci 2013. [DOI: 10.1016/j.cocis.2013.07.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Guitchounts G, Markowitz JE, Liberti WA, Gardner TJ. A carbon-fiber electrode array for long-term neural recording. J Neural Eng 2013; 10:046016. [PMID: 23860226 DOI: 10.1088/1741-2560/10/4/046016] [Citation(s) in RCA: 141] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Chronic neural recording in behaving animals is an essential method for studies of neural circuit function. However, stable recordings from small, densely packed neurons remains challenging, particularly over time-scales relevant for learning. APPROACH We describe an assembly method for a 16-channel electrode array consisting of carbon fibers (<5 µm diameter) individually insulated with Parylene-C and fire-sharpened. The diameter of the array is approximately 26 µm along the full extent of the implant. MAIN RESULTS Carbon fiber arrays were tested in HVC (used as a proper name), a song motor nucleus, of singing zebra finches where individual neurons discharge with temporally precise patterns. Previous reports of activity in this population of neurons have required the use of high impedance electrodes on movable microdrives. Here, the carbon fiber electrodes provided stable multi-unit recordings over time-scales of months. Spike-sorting indicated that the multi-unit signals were dominated by one, or a small number of cells. Stable firing patterns during singing confirmed the stability of these clusters over time-scales of months. In addition, from a total of 10 surgeries, 16 projection neurons were found. This cell type is characterized by sparse stereotyped firing patterns, providing unambiguous confirmation of single cell recordings. SIGNIFICANCE Carbon fiber electrode bundles may provide a scalable solution for long-term neural recordings of densely packed neurons.
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Affiliation(s)
- Grigori Guitchounts
- Department of Biology, Boston University, 24 Cummington Mall, Boston, MA 02215, USA
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Intracellular Neural Recording with Pure Carbon Nanotube Probes. PLoS One 2013; 8:e65715. [PMID: 23840357 PMCID: PMC3686779 DOI: 10.1371/journal.pone.0065715] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Accepted: 05/01/2013] [Indexed: 11/19/2022] Open
Abstract
The computational complexity of the brain depends in part on a neuron’s capacity to integrate electrochemical information from vast numbers of synaptic inputs. The measurements of synaptic activity that are crucial for mechanistic understanding of brain function are also challenging, because they require intracellular recording methods to detect and resolve millivolt- scale synaptic potentials. Although glass electrodes are widely used for intracellular recordings, novel electrodes with superior mechanical and electrical properties are desirable, because they could extend intracellular recording methods to challenging environments, including long term recordings in freely behaving animals. Carbon nanotubes (CNTs) can theoretically deliver this advance, but the difficulty of assembling CNTs has limited their application to a coating layer or assembly on a planar substrate, resulting in electrodes that are more suitable for in vivo extracellular recording or extracellular recording from isolated cells. Here we show that a novel, yet remarkably simple, millimeter-long electrode with a sub-micron tip, fabricated from self-entangled pure CNTs can be used to obtain intracellular and extracellular recordings from vertebrate neurons in vitro and in vivo. This fabrication technology provides a new method for assembling intracellular electrodes from CNTs, affording a promising opportunity to harness nanotechnology for neuroscience applications.
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Xie X, Xu AM, Angle MR, Tayebi N, Verma P, Melosh NA. Mechanical model of vertical nanowire cell penetration. NANO LETTERS 2013; 13:6002-8. [PMID: 24237230 DOI: 10.1021/nl403201a] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Direct access into cells' interiors is essential for biomolecular delivery, gene transfection, and electrical recordings yet is challenging due to the cell membrane barrier. Recently, molecular delivery using vertical nanowires (NWs) has been demonstrated for introducing biomolecules into a large number of cells in parallel. However, the microscopic understanding of how and when the nanowires penetrate cell membranes is still lacking, and the degree to which actual membrane penetration occurs is controversial. Here we present results from a mechanical continuum model of elastic cell membrane penetration through two mechanisms, namely through "impaling" as cells land onto a bed of nanowires, and through "adhesion-mediated" penetration, which occurs as cells spread on the substrate and generate adhesion force. Our results reveal that penetration is much more effective through the adhesion mechanism, with NW geometry and cell stiffness being critically important. Stiffer cells have higher penetration efficiency, but are more sensitive to NW geometry. These results provide a guide to designing nanowires for applications in cell membrane penetration.
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Affiliation(s)
- Xi Xie
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
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