scholarly journals Nanofibrous PEDOT-Carbon Composite on Flexible Probes for Soft Neural Interfacing

2021 ◽  
Vol 9 ◽  
Author(s):  
Venkata Suresh Vajrala ◽  
Valentin Saunier ◽  
Lionel G. Nowak ◽  
Emmanuel Flahaut ◽  
Christian Bergaud ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Carbon Nanofiber ◽  
Electrochemical Polymerization ◽  
High Surface ◽  
Electrochemical Characterizations ◽  
Brain Slices ◽  
Composite Electrodes ◽  
Field Potentials ◽  
Porous Network

In this study, we report a flexible implantable 4-channel microelectrode probe coated with highly porous and robust nanocomposite of poly (3,4-ethylenedioxythiophene) (PEDOT) and carbon nanofiber (CNF) as a solid doping template for high-performance in vivo neuronal recording and stimulation. A simple yet well-controlled deposition strategy was developed via in situ electrochemical polymerization technique to create a porous network of PEDOT and CNFs on a flexible 4-channel gold microelectrode probe. Different morphological and electrochemical characterizations showed that they exhibit remarkable and superior electrochemical properties, yielding microelectrodes combining high surface area, low impedance (16.8 ± 2 MΩ µm2 at 1 kHz) and elevated charge injection capabilities (7.6 ± 1.3 mC/cm2) that exceed those of pure and composite PEDOT layers. In addition, the PEDOT-CNF composite electrode exhibited extended biphasic charge cycle endurance and excellent performance under accelerated lifetime testing, resulting in a negligible physical delamination and/or degradation for long periods of electrical stimulation. In vitro testing on mouse brain slices showed that they can record spontaneous oscillatory field potentials as well as single-unit action potentials and allow to safely deliver electrical stimulation for evoking field potentials. The combined superior electrical properties, durability and 3D microstructure topology of the PEDOT-CNF composite electrodes demonstrate outstanding potential for developing future neural surface interfacing applications.

scholarly journals Nanofibrous PEDOT-Carbon Composite on Flexible Probes for Soft Neural Interfacing

2021 ◽  
Author(s):  
venkata suresh vajrala ◽  
valentin Saunier ◽  
Lionel G Nowak ◽  
Emmanuel Flahaut ◽  
Christian Bergaud ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Carbon Nanofiber ◽  
Electrochemical Polymerization ◽  
High Surface ◽  
Electrochemical Characterizations ◽  
Brain Slices ◽  
Composite Electrodes ◽  
Field Potentials ◽  
Porous Network

In this study, we report a flexible implantable 4-channel microelectrode probe coated with highly porous and robust nanocomposite of poly(3,4-ethylenedioxythiophene) (PEDOT) and carbon nanofiber (CNF) as a solid doping template for high-performance in vivo neuronal recording and stimulation. A simple yet well-controlled deposition strategy was developed via in situ electrochemical polymerization technique to create a porous network of PEDOT and CNFs on a flexible 4-channel gold microelectrode probe. Different morphological and electrochemical characterizations showed that they exhibit remarkable and superior electrochemical properties, yielding microelectrodes combining high surface area, low impedance (16.8 Mohm.micrometer2 at 1 kHz) and elevated charge injection capabilities (7.6 mC/cm2) that exceed those of pure and composite PEDOT layers. In addition, the PEDOT-CNF composite electrode exhibited extended biphasic charge cycle endurance, resulting in a negligible physical delamination or degradation for long periods of electrical stimulation. In vitro testing on mouse brain slices showed that they can record spontaneous oscillatory field potentials as well as single-unit action potentials and allow to safely deliver electrical stimulation for evoking field potentials. The combined superior electrical properties, durability and 3D microstructure topology of the PEDOT-CNF composite electrodes demonstrate outstanding potential for developing future neural surface interfacing applications

Differential conditioning of associative synaptic enhancement in hippocampal brain slices

Science ◽  
1986 ◽  
Vol 232 (4746) ◽  
pp. 85-87 ◽  
Author(s):  
Kelso ◽  
TH Brown
Keyword(s):  
Electrical Stimulation ◽  
High Frequency ◽  
Differential Conditioning ◽  
Pyramidal Neurons ◽  
Brain Slices ◽  
Synaptic Inputs ◽  
Hippocampal Synapses ◽  
Stimulation Paradigm ◽  
Stimulation Of

An electrophysiological stimulation paradigm similar to one that produces Pavlovian conditioning was applied to synaptic inputs to pyramidal neurons of hippocampal brain slices. Persistent synaptic enhancement was induced in one of two weak synaptic inputs by pairing high-frequency electrical stimulation of the weak input with stimulation of a third, stronger input to the same region. Forward (temporally overlapping) but not backward (temporally separate) pairings caused this enhancement. Thus hippocampal synapses in vitro can undergo the conditional and selective type of associative modification that could provide the substrate for some of the mnemonic functions in which the hippocampus is thought to participate.

Small Diameter, High Surface Energy Carbon Nanofiber Formulations that Selectively Increase Osteoblast Function

2001 ◽  
Vol 711 ◽  
Author(s):  
Rachel L. Price ◽  
Kathy L. Elias ◽  
Karen M. Haberstroh ◽  
Thomas J. Webster
Keyword(s):  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Carbon Nanofibers ◽  
Alkaline Phosphatase Activity ◽  
Carbon Nanofiber ◽  
High Surface ◽  
Small Diameter ◽  
Calcium Deposition ◽  
Time Points

ABSTRACTThe objective of the present in vitro study was to investigate the potential of carbon nanofibers, which have nanometer dimensions similar to hydroxyapatite crystals in physiological bone, for orthopedic applications. Studies of alkaline phosphatase activity and calcium deposition by osteoblasts (the bone-synthesizing cells) were performed on both nanophase (less than 100 nm) and conventional (greater than 100 nm) diameter carbon nanofibers. Results provided the first evidence of a strong correlation between decreased carbon fiber diameter and both increased alkaline phosphatase activity and increased calcium deposition by osteoblasts at early time points (specifically, 7 days), but not at later time points (specifically, 14 and 21 days). Results of early calcium deposition by osteoblasts on carbon nanofibers are promising and consistent with the desired rapid formation of natural bone at the implant interface.

scholarly journals Stimjim: open source hardware for precise electrical stimulation

2019 ◽  
Author(s):  
Nathan Cermak ◽  
Matthew A. Wilson ◽  
Jackie Schiller ◽  
Jonathan P. Newman
Keyword(s):  
Electrical Stimulation ◽  
Open Source ◽  
Brain Slices ◽  
Brain Stimulation Reward ◽  
Reward Seeking ◽  
Seeking Behavior ◽  
Open Source Hardware ◽  
Closed Source

AbstractElectrical stimulation is a simple and powerful tool to perturb and evoke neuronal activity in order to understand the function of neurons and neural circuits. Despite this, devices that can provide precise current or voltage stimulation are expensive and closed-source. Here, we introduce Stimjim, a capable and inexpensive ($200 USD) open-source instrument for electrical stimulation that combines both function generation and electrical isolation. Stimjim provides microsecond temporal resolution with microampere or millivolt scale precision on two electrically isolated output channels. We demonstrate Stimjim’s utility both in vitro by precisely stimulating brain slices, and in vivo by training mice to perform intracranial self-stimulation (ICSS) for brain stimulation reward. During ICSS, Stimjim enables the experimenter to smoothly tune the strength of reward-seeking behavior by varying either the output frequency or amplitude. We envision Stimjim will enable new kinds of experiments due to its open-source and scalable nature.

Cellular Mechanisms Underlying Antiepileptic Effects of Low- and High-Frequency Electrical Stimulation in Acute Epilepsy in Neocortical Brain Slices In Vitro

2007 ◽  
Vol 97 (3) ◽  
pp. 1887-1902 ◽  
Author(s):  
Yitzhak Schiller ◽  
Yael Bankirer
Keyword(s):  
Electrical Stimulation ◽  
High Frequency ◽  
Brain Slices ◽  
Low Frequency ◽  
High Frequency Stimulation ◽  
Dependent Manner ◽  
Cellular Mechanisms ◽  
Epileptiform Discharges ◽  
Frequency Stimulation

Approximately 30% of epilepsy patients suffer from drug-resistant epilepsy. Direct electrical stimulation of the epileptogenic zone is a potential new treatment modality for this devastating disease. In this study, we investigated the effect of two electrical stimulation paradigms, sustained low-frequency stimulation and short trains of high-frequency stimulation, on epileptiform discharges in neocortical brain slices treated with either bicuculline or magnesium-free extracellular solution. Sustained low-frequency stimulation (5–30 min of 0.1- to 5-Hz stimulation) prevented both interictal-like discharges and seizure-like events in an intensity-, frequency-, and distance-dependent manner. Short trains of high-frequency stimulation (1–5 s of 25- to 200-Hz stimulation) prematurely terminated seizure-like events in a frequency-, intensity-, and duration-dependent manner. Roughly one half the seizures terminated within the 100-Hz stimulation train ( P < 0.01 compared with control), whereas the remaining seizures were significantly shortened by 53 ± 21% ( P < 0.01). Regarding the cellular mechanisms underlying the antiepileptic effects of electrical stimulation, both low- and high-frequency stimulation markedly depressed excitatory postsynaptic potentials (EPSPs). The EPSP amplitude decreased by 75 ± 3% after 10-min, 1-Hz stimulation and by 86 ± 6% after 1-s, 100-Hz stimulation. Moreover, partial pharmacological blockade of ionotropic glutamate receptors was sufficient to suppress epileptiform discharges and enhance the antiepileptic effects of stimulation. In conclusion, this study showed that both low- and high-frequency electrical stimulation possessed antiepileptic effects in the neocortex in vitro, established the parameters determining the antiepileptic efficacy of both stimulation paradigms, and suggested that the antiepileptic effects of stimulation were mediated mostly by short-term synaptic depression of excitatory neurotransmission.

Improved Cardiomyocyte Functions of Carbon Nanofiber Cardiac Patches

2012 ◽  
Vol 1417 ◽  
Author(s):  
David A. Stout ◽  
Emilia Raimondo ◽  
Thomas J. Webster
Keyword(s):  
Electrical Stimulation ◽  
Glycolic Acid ◽  
Troponin I ◽  
Carbon Nanofiber ◽  
Myocardial Tissue ◽  
Human Cardiomyocytes ◽  
Cell Functions ◽  
Stimulation System ◽  
Myocardial Tissue Engineering

ABSTRACTThe objective of the present in vitro research was to determine cardiomyocyte functions on poly-lactic-co-glycolic acid (50:50 (PLA:PGA); PLGA) with greater amounts of carbon nanofibers (CNFs) using an in vitro electrical stimulation system for myocardial tissue engineering applications. The addition of CNFs can increase the conductivity and strength of pure PLGA. For this reason, different PLGA: CNF ratios (100:0, 75:25, 50:50, 25:75, 0:100 wt%) were created where conductivity and cytocompatibility properties under electrical stimulation with human cardiomyocytes were determined. Results showed that PLGA:CNF materials were conductive and that conductivity increased with greater amounts of PLGA added, from 0 S.m-1 for 100:0 wt% (pure PLGA) to 6.5x10-3 S.m-1 for 0:100 wt% (pure CNFs) materials. Furthermore, results indicated that cardiomyocyte cell density increased with continuous electrical stimulation (rectangular, 2 nm, 5 V/cm, 1 Hz) after 1, 3, and 5 days as well as a slight increase in Troponin I excretion compared to non-electrically stimulated normal cardiomyocyte cell functions. This study, thus, provides an alternative conductive scaffold using nanotechnology which should be further explored for numerous cardiovascular applications.

scholarly journals Epileptiform activity in mouse hippocampal slices induced by moderate changes in extracellular Mg2+, Ca2+, and K+

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Haiyu Liu ◽  
Sai Zhang ◽  
Liang Zhang
Keyword(s):  
Prolonged Exposure ◽  
Epileptiform Activity ◽  
Hippocampal Slices ◽  
Brain Slices ◽  
Experimental Investigations ◽  
High Frequency Stimulation ◽  
Field Potentials ◽  
Epileptiform Discharges ◽  
Frequency Stimulation

Abstract Background Rodent brain slices—particularly hippocampal slices—are widely used in experimental investigations of epileptiform activity. Oxygenated artificial cerebrospinal fluid (ACSF) is used to maintain slices in vitro. Physiological or standard ACSF containing 3–3.5 mM K+, 1–2 mM Mg2+, and 1–3 mM Ca2+ generally does not induce population epileptiform activity, which can be induced by ACSF with high K+ (8–10 mM), low Mg2+, or low Ca2+ alone or in combination. While low-Mg2+ ACSF without intentionally added Mg salt but with contaminating Mg2+ (≤ 50–80 µM) from other salts can induce robust epileptiform activity in slices, it is unclear whether such epileptiform activity can be achieved using ACSF with moderately decreased Mg2+. To explore this issue, we examined the effects of moderately modified (m)ACSF with 0.8 mM Mg2+, 1.3 mM Ca2+, and 5.7 mM K+ on induction of epileptiform discharges in mouse hippocampal slices. Results Hippocampal slices were prepared from young (21–28 days old), middle-aged (13–14 months old), and aged (24–26 months old) C57/BL6 mice. Conventional thin (0.4 mm) and thick (0.6 mm) slices were obtained using a vibratome and pretreated with mACSF at 35–36 °C for 1 h prior to recordings. During perfusion with mACSF at 35–36 °C, spontaneous or self-sustained epileptiform field potentials following high-frequency stimulation were frequently recorded in slices pretreated with mACSF but not in those without the pretreatment. Seizure-like ictal discharges were more common in thick slices than in thin slices. Conclusions Prolonged exposure to mACSF by pretreatment and subsequent perfusion can induce epileptiform field potentials in mouse hippocampal slices.

LY53857, a 5HT2 Receptor Antagonist, Delays Occlusion and Inhibits Platelet Aggregation in a Rabbit Model of Carotid Artery Occlusion

1991 ◽  
Vol 66 (03) ◽  
pp. 355-360 ◽  
Author(s):  
Harve C Wilson ◽  
William Coffman ◽  
Anne L Killam ◽  
Marlene L Cohen
Keyword(s):  
Electrical Stimulation ◽  
Platelet Aggregation ◽  
Carotid Artery ◽  
Receptor Antagonist ◽  
Artery Occlusion ◽  
Carotid Artery Occlusion ◽  
Rabbit Platelet ◽  
Rabbit Platelets ◽  
5Ht2 Receptor

SummaryThe present study was designed to evaluate the effectiveness of the ergoline 5HT2 receptor antagonist, LY53857 in a rabbit model of vascular arterial occlusion. LY53857 (1 and 10 εM) inhibited serotonin amplified platelet aggregation responses to threshold concentrations of ADP in rabbit platelets in vitro. LY53857 (1 εM) not only inhibited the serotonin component of rabbit platelet aggregation, but also inhibited in vitro aggregation induced by ADP (48.7 ± 16.7% inhibition), collagen (76.1 ± 15.9% inhibition) and U46619 (65.2 ± 12.3% inhibition). The effectiveness of this ergoline 5HT2 receptor antagonist in blocking aggregation to ADP, collagen and U46619 may be related to its ability to inhibit a serotonin component of platelet aggregation since rabbit platelets possess high concentrations of serotonin that may be released during aggregation produced by other agents. Based on the effectiveness of LY53857 to inhibit rabbit platelet aggregation, we explored the ability of LY53857 to extend the time to carotid artery occlusion in rabbits following electrical stimulation of the artery. Reproducible carotid artery occlusion was induced in rabbits by moderate stenosis coupled to arterial cross clamping, followed by electrical stimulation. With this procedure, occlusion occurred at 47.0 ± 7 min (n = 30) after initiation of the electrical stimulation. Animals pretreated with LY53857 (50 to 500 εg/kg i.v.) showed a delay in the time to carotid artery occlusion (at 100 εg/kg i.v. occlusion time extended to 164 ± 16 min). Furthermore, ex vivo platelet aggregation from animals treated with LY53857 (300 εg/kg i.v.) resulted in 40.5% inhibition of platelet aggregation in response to the combination of ADP (1 εM) and serotonin (1 εM). These studies document the ability to obtain reproducible arterial occlusion in the rabbit and showed that intravenously administered LY53857 prolonged the time to carotid artery occlusion. Prolongation of carotid artery occlusion time was accompanied by inhibition of serotonin-amplified ADP-induced aggregation in rabbit platelets, an effect observed both in vitro and ex vivo. Thus, the rabbit is a useful model for studying the effectiveness of 5HT2 receptor antagonists in prolonging vascular occlusion induced by insult of the carotid artery.

Cytocompatibility and Material Properties of Poly-carbonate Urethane/Carbon Nanofiber Composites for Neural Applications

2003 ◽  
Vol 774 ◽  
Author(s):  
Janice L. McKenzie ◽  
Michael C. Waid ◽  
Riyi Shi ◽  
Thomas J. Webster
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanofibers ◽  
Material Properties ◽  
Carbon Nanofiber ◽  
Scar Tissue ◽  
Tissue Response ◽  
Positive Interactions ◽  
Weight Percentage ◽  
Poly Carbonate

AbstractCarbon nanofibers possess excellent conductivity properties, which may be beneficial in the design of more effective neural prostheses, however, limited evidence on their cytocompatibility properties exists. The objective of the present in vitro study was to determine cytocompatibility and material properties of formulations containing carbon nanofibers to predict the gliotic scar tissue response. Poly-carbonate urethane was combined with carbon nanofibers in varying weight percentages to provide a supportive matrix with beneficial bulk electrical and mechanical properties. The substrates were tested for mechanical properties and conductivity. Astrocytes (glial scar tissue-forming cells) were seeded onto the substrates for adhesion. Results provided the first evidence that astrocytes preferentially adhered to the composite material that contained the lowest weight percentage of carbon nanofibers. Positive interactions with neurons, and, at the same time, limited astrocyte functions leading to decreased gliotic scar tissue formation are essential for increased neuronal implant efficacy.

Intercalation of First Row Transition Metals inside Covalent-Organic Frameworks (COF): a Strategy to Fine Tune the Electronic Properties of Porous Crystalline Materials

2018 ◽  
Author(s):  
Srimanta Pakhira ◽  
Jose Mendoza-Cortes
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Electronic Properties ◽  
High Surface ◽  
Electronic Devices ◽  
High Surface Area ◽  
Main Role ◽  
Covalent Organic Frameworks ◽  
Porous Network ◽  
Crystalline Materials

<div>Covalent organic frameworks (COFs) have emerged as an important class of nano-porous crystalline materials with many potential applications. They are intriguing platforms for the design of porous skeletons with special functionality at the molecular level. However, despite their extraordinary properties, it is difficult to control their electronic properties, thus hindering the potential implementation in electronic devices. A new form of nanoporous material, COFs intercalated with first row transition metal is proposed to address this fundamental drawback - the lack of electronic tunability. Using first-principles calculations, we have designed 31 new COF materials <i>in-silico</i> by intercalating all of the first row transition metals (TMs) with boroxine-linked and triazine-linked COFs: COF-TM-x (where TM=Sc-Zn and x=3-5). This is a significant addition considering that only 187 experimentally COFs structures has been reported and characterized so far. We have investigated their structure and electronic properties. Specifically, we predict that COF's band gap and density of states (DOSs) can be controlled by intercalating first row transition metal atoms (TM: Sc - Zn) and fine tuned by the concentration of TMs. We also found that the $d$-subshell electron density of the TMs plays the main role in determining the electronic properties of the COFs. Thus intercalated-COFs provide a new strategy to control the electronic properties of materials within a porous network. This work opens up new avenues for the design of TM-intercalated materials with promising future applications in nanoporous electronic devices, where a high surface area coupled with fine-tuned electronic properties are desired.</div>

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