Micro- and nanotechnology for neural electrode-tissue interfaces.
TL;DR: This review focuses on the latest developments for the optimization of neural electrode-tissue interfaces, including electrode materials, electrode structures, nano-coatings and hydrogel-based neural interfaces, which can effectively improve the long-term stability and the chronic inflammatory response of neural interfaces during the recording and modulation of biosignals.
About: This article is published in Biosensors and Bioelectronics.The article was published on 2020-12-15. It has received 36 citations till now. The article focuses on the topics: Chronic inflammatory response.
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TL;DR: In this article, the authors show that the dynamics of water molecules solvating polyethers is fundamentally different depending on their C/O composition, which is not because of steric effects, but because the partial charge on the O atoms depends on the number of atoms by which they are separated.
Abstract: The solubilities of polyethers are surprisingly counter-intuitive. The best-known example is the difference between polyethylene glycol ([–CH2–CH2–O–]n) which is infinitely soluble, and polyoxymethylene ([–CH2–O–]n) which is completely insoluble in water, exactly the opposite of what one expects from the C/O ratios of these molecules. Similar anomalies exist for oligomeric and cyclic polyethers. To solve this apparent mystery, we use femtosecond vibrational and GHz dielectric spectroscopy with complementary ab initio calculations and molecular dynamics simulations. We find that the dynamics of water molecules solvating polyethers is fundamentally different depending on their C/O composition. The ab initio calculations and simulations show that this is not because of steric effects (as is commonly believed), but because the partial charge on the O atoms depends on the number of C atoms by which they are separated. Our results thus show that inductive effects can have a major impact on aqueous solubilities.Polyethers are ubiquitous in our daily lives, and display counterintuitive solubilities in water. Here the authors show, by ultrafast spectroscopies and computations, that solubility does not depend on steric factors but on the interaction of water molecules with the polymer’s charge distribution
51 citations
01 Feb 2019
TL;DR: Examples of fiber-based neural probes tailored to the electrophysiological recording, optical neuromodulation, and delivery of drugs and genes into the rodent brain and spinal cord are discussed, as are their emerging use for studies of nerve growth and repair.
Abstract: United States. National Institute of Neurological Disorders and Stroke (Grant 5R01NS086804)
47 citations
TL;DR: Wang et al. as discussed by the authors developed a stable clay-based nanocomposite hydrogel using 4-acryloylmorpholine as the monomer after UV light illumination.
Abstract: Although clay-based nanocomposite hydrogels have been widely explored, their instability in hot water and saline solution inhibits their applications in biomedical engineering, and the exploration of clay-based nanocomposite hydrogels in bone defect repair is even less. In this work, we developed a stable clay-based nanocomposite hydrogel using 4-acryloylmorpholine as the monomer. After UV light illumination, the obtained poly(4-acryloylmorpholine) clay-based nanocomposite hydrogel (poly(4-acry)-clay nanocomposite hydrogel) exhibits excellent mechanical properties due to the hydrogen bond interactions between the poly(4-acryloylmorpholine) chains and the physical crosslinking effect of the nanoclay. Besides good biocompatibility, the sustainable release of intrinsic Mg2+ and Si4+ from the poly(4-acry)-clay nanocomposite hydrogel endows the system with excellent ability to promote the osteogenic differentiation of primary rat osteoblasts (ROBs) and can promote new bone formation effectively after implantation. We anticipate that these kinds of clay-based nanocomposite hydrogels with sustained release of bioactive ions will open a new avenue for the development of novel biomaterials for bone regeneration.
15 citations
TL;DR: In this paper , the authors reviewed the latest research methods and strategies for improving the electrochemical performance and biocompatibility of neural electrodes and proposed challenges in the development of Neural electrodes.
Abstract: Neural electrodes, as a bridge for bidirectional communication between the body and external devices, are crucial means for detecting and controlling nerve activity. The electrodes play a vital role in monitoring the state of neural systems or influencing it to treat disease or restore functions. To achieve high-resolution, safe and long-term stable nerve recording and stimulation, a neural electrode with excellent electrochemical performance (e.g., impedance, charge storage capacity, charge injection limit), and good biocompatibility and stability is required. Here, the charge transfer process in the tissues, the electrode-tissue interfaces and the electrode materials are discussed respectively. Subsequently, the latest research methods and strategies for improving the electrochemical performance and biocompatibility of neural electrodes are reviewed. Finally, the challenges in the development of neural electrodes are proposed. It is expected that the development of neural electrodes will offer new opportunities for the evolution of neural prosthesis, bioelectronic medicine, brain science, and so on.
12 citations
TL;DR: This review points out a number of conceptual tools to further address the ongoing advances in coupling neuronal networks with (carbon) nanotube meshworks, and to deepen the basic issues that govern a biological cell or tissue interacting with a nanomaterial.
12 citations
References
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TL;DR: High-density recordings of field activity in animals and subdural grid recordings in humans can provide insight into the cooperative behaviour of neurons, their average synaptic input and their spiking output, and can increase the understanding of how these processes contribute to the extracellular signal.
Abstract: Neuronal activity in the brain gives rise to transmembrane currents that can be measured in the extracellular medium. Although the major contributor of the extracellular signal is the synaptic transmembrane current, other sources — including Na+ and Ca2+ spikes, ionic fluxes through voltage- and ligand-gated channels, and intrinsic membrane oscillations — can substantially shape the extracellular field. High-density recordings of field activity in animals and subdural grid recordings in humans, combined with recently developed data processing tools and computational modelling, can provide insight into the cooperative behaviour of neurons, their average synaptic input and their spiking output, and can increase our understanding of how these processes contribute to the extracellular signal.
3,366 citations
TL;DR: In this article, electrical transport measurements on individual single-wall nanotubes have been performed to confirm the theoretical predictions of single-walled nanotube quantum wires, and they have been shown to act as genuine quantum wires.
Abstract: Carbon nanotubes have been regarded since their discovery1 as potential molecular quantum wires. In the case of multi-wall nanotubes, where many tubes are arranged in a coaxial fashion, the electrical properties of individual tubes have been shown to vary strongly from tube to tube2,3, and to be characterized by disorder and localization4. Single-wall nanotubes5,6 (SWNTs) have recently been obtained with high yields and structural uniformity7. Particular varieties of these highly symmetric structures have been predicted to be metallic, with electrical conduction occurring through only two electronic modes8–10. Because of the structural symmetry and stiffness of SWNTs, their molecular wavefunctions may extend over the entire tube. Here we report electrical transport measurements on individual single-wall nanotubes that confirm these theoretical predictions. We find that SWNTs indeed act as genuine quantum wires. Electrical conduction seems to occur through well separated, discrete electron states that are quantum-mechanically coherent over long distance, that is at least from contact to contact (140nm). Data in a magnetic field indicate shifting of these states due to the Zeeman effect.
2,678 citations
TL;DR: An integrated tissue–organ printer (ITOP) that can fabricate stable, human-scale tissue constructs of any shape is presented and the incorporation of microchannels into the tissue constructs facilitates diffusion of nutrients to printed cells, thereby overcoming the diffusion limit of 100–200 μm for cell survival in engineered tissues.
Abstract: A challenge for tissue engineering is producing three-dimensional (3D), vascularized cellular constructs of clinically relevant size, shape and structural integrity. We present an integrated tissue-organ printer (ITOP) that can fabricate stable, human-scale tissue constructs of any shape. Mechanical stability is achieved by printing cell-laden hydrogels together with biodegradable polymers in integrated patterns and anchored on sacrificial hydrogels. The correct shape of the tissue construct is achieved by representing clinical imaging data as a computer model of the anatomical defect and translating the model into a program that controls the motions of the printer nozzles, which dispense cells to discrete locations. The incorporation of microchannels into the tissue constructs facilitates diffusion of nutrients to printed cells, thereby overcoming the diffusion limit of 100-200 μm for cell survival in engineered tissues. We demonstrate capabilities of the ITOP by fabricating mandible and calvarial bone, cartilage and skeletal muscle. Future development of the ITOP is being directed to the production of tissues for human applications and to the building of more complex tissues and solid organs.
1,960 citations
TL;DR: Techniques for characterizing electrochemical properties relevant to stimulation and recording are described with examples of differences in the in vitro and in vivo response of electrodes.
Abstract: Electrical stimulation of nerve tissue and recording of neural electrical activity are the basis of emerging prostheses and treatments for spinal cord injury, stroke, sensory deficits, and neurological disorders. An understanding of the electrochemical mechanisms underlying the behavior of neural stimulation and recording electrodes is important for the development of chronically implanted devices, particularly those employing large numbers of microelectrodes. For stimulation, materials that support charge injection by capacitive and faradaic mechanisms are available. These include titanium nitride, platinum, and iridium oxide, each with certain advantages and limitations. The use of charge-balanced waveforms and maximum electrochemical potential excursions as criteria for reversible charge injection with these electrode materials are described and critiqued. Techniques for characterizing electrochemical properties relevant to stimulation and recording are described with examples of differences in the in vitro and in vivo response of electrodes.
1,843 citations
TL;DR: In this article, the theoretical external specific surface area of single and multi-walled carbon nanotubes and of carbon-nanotube bundles is calculated as a function of their characteristics.
1,836 citations