Carbon Fiber Electrodes Research Articles

Quantal Release of Dopamine and Action Potential Firing Detected in Midbrain Neurons by Multifunctional Diamond-Based Microarrays.

Micro-Graphitic Single Crystal Diamond Multi Electrode Arrays (μG-SCD-MEAs) have so far been used as amperometric sensors to detect catecholamines from chromaffin cells and adrenal gland slices. Besides having time resolution and sensitivity that are comparable with carbon fiber electrodes, that represent the gold standard for amperometry, μG-SCD-MEAs also have the advantages of simultaneous multisite detection, high biocompatibility and implementation of amperometric/potentiometric protocols, aimed at monitoring exocytotic events and neuronal excitability. In order to adapt diamond technology to record neuronal activity, the μG-SCD-MEAs in this work have been interfaced with cultured midbrain neurons to detect electrical activity as well as quantal release of dopamine (DA). μG-SCD-MEAs are based on graphitic sensing electrodes that are embedded into the diamond matrix and are fabricated using MeV ion beam lithography. Two geometries have been adopted, with 4 × 4 and 8 × 8 microelectrodes (20 μm × 3.5 μm exposed area, 200 μm spacing). In the amperometric configuration, the 4 × 4 μG-SCD-MEAs resolved quantal exocytosis from midbrain dopaminergic neurons. KCl-stimulated DA release occurred as amperometric spikes of 15 pA amplitude and 0.5 ms half-width, at a mean frequency of 0.4 Hz. When used as potentiometric multiarrays, the 8 × 8 μG-SCD-MEAs detected the spontaneous firing activity of midbrain neurons. Extracellularly recorded action potentials (APs) had mean amplitude of ∼-50 μV and occurred at a mean firing frequency of 0.7 Hz in 67% of neurons, while the remaining fired at 6.8 Hz. Comparable findings were observed using conventional MEAs (0.9 and 6.4 Hz, respectively). To test the reliability of potentiometric recordings with μG-SCD-MEAs, the D2-autoreceptor modulation of firing was investigated by applying levodopa (L-DOPA, 20 μM), and comparing μG-SCD-MEAs, conventional MEAs and current-clamp recordings. In all cases, L-DOPA reduced the spontaneous spiking activity in most neurons by 70%, while the D2-antagonist sulpiride reversed this effect. Cell firing inhibition was generally associated with increased APs amplitude. A minority of neurons was either insensitive to, or potentiated by L-DOPA, suggesting that AP recordings originate from different midbrain neuronal subpopulations and reveal different modulatory pathways. Our data demonstrate, for the first time, that μG-SCD-MEAs are multi-functional biosensors suitable to resolve real-time DA release and AP firing in in vitro neuronal networks.

Sympathetic Neurotransmission in Resistance Mesenteric Arteries in Obesity‐Related Hypertension

Hyperactivity of sympathetic nerves has an important role in the pathogenesis of obesity‐related hypertension. The mechanisms linking obesity to hypertension are unclear. Small mesenteric arteries (MA, <300 mm dia.) are resistance blood vessels that are densely innervated by sympathetic nerves. Nerve varicosities release norepinephrine (NE) and ATP which cause arterial constriction. Impaired control of NE and/or ATP release and clearance would cause hypertension. Alterations in sympathetic nerves supplying MAs contribute to hypertension in several animal models. This study examined whether alterations of sympathetic neurotransmission in the resistance MAs contribute to high blood pressure in high fat‐fed (HF) Dahl salt‐sensitive rats. Sympathetic nerves supplying MAs maintained in vitro were stimulated focally. Electrically‐evoked NE and ATP release were detected by using amperometry with carbon fiber electrodes, and intracellular recording of excitatory junction potentials (EJPs) from arterial smooth muscle cells, respectively. Data were obtained from male and female rats at 10, 17, and 24 weeks of control and HF diet. Peak amplitudes of NE oxidation current and EJPs were assessed. NE oxidation current from all groups were blocked by a Na+ channel blocker, tetrodotoxin (TTX, 300 nM), suggesting that NE release in neurogenic. EJPs from all groups were abolished by TTX, and PPADS (10 μM), a P2X receptor antagonist, indicating that EJPs were neurogenic and purinergic. Frequency (1–30 Hz, 50 pulses) response curves using amperometric measurement of NE release showed similar responses in MAs from control and HF fed male and female rats. EJP frequency (0.5–10Hz, 5 pulses) response curves were also similar in MA from control and HF fed male and female rats. We investigated prejunctional α2‐adrenergic receptor function using the α2 receptor agonist (UK14,304) and antagonist (yohimbine). UK14,304 (0.0001–10 μM) inhibited NE and ATP release equally well and in a concentration‐dependent manner in MAs from control and HF rats. In the presence of 1 μM yohimbine, NE and ATP release was increased equally in MA from all rats. We conclude that adrenergic and purinergic neurotransmission by periarterial sympathetic nerves are not affected in HF Dahl salt sensitive rats. Elevated blood pressure in this animal model is not dependent on altered sympathetic neurotransmission to the mesenteric vasculature.Support or Funding InformationNIH 2P01HL070687 (For JJG), and Post‐doctoral training scholarship, Faculty of Medicine, Thammasat University, Thailand (For SS).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

In Vivo Measurement of Calcium Ion with Solid-State Ion-Selective Electrode by Using Shelled Hollow Carbon Nanospheres as a Transducing Layer.

In vivo monitoring of extracellular calcium ion (Ca2+) is of great importance due to its significant contributions in different (patho)physiological processes. In this study, we develop a potentiometric method with solid-state ion-selective electrodes (ISEs) for in vivo monitoring of the dynamics of the extracellular Ca2+ by using hollow carbon nanospheres (HCNs) as a transducing layer and solid contact to efficiently promote the ion-to-electron transduction between an ionophore-doped solvated polymeric membrane and a conducting substrate. We find that the use of HCNs essentially improves the stability of the signal response and minimizes the potential drift of the as-prepared ISEs. With three-shelled HCNs (3s-HCNs) as the transducing layer, we fabricate a solid-state Ca2+-selective microelectrode by forming a Ca2+-selective membrane with calcium ionophore II as the recognition unit, 2-nitrophenyl octyl ether as the plasticizer, sodium tetrakis[3,5-bis(trifluoromethyl)phenyl] borate as the ion exchanger, and polyvinyl chloride polymeric as the matrix onto the 3s-HCN-modified carbon fiber electrodes. The as-prepared electrode shows a high stability and a near Nernst response of 28 mV/decade toward Ca2+ over a concentration range from 10-5 to 0.05 M as well as a good selectivity against species endogenously existing in the central nervous system. With these properties, the electrode is used for real-time recording of the dynamics of extracellular Ca2+ during spreading depression induced by electrical stimulation, in which the extracellular Ca2+ in rat cortex is found to decrease by 50.0 ± 7.5% ( n = 5) during spreading depression. This study essentially offers a new platform to develop solid-state ISEs, which is particularly useful for in vivo measurements of metal ions and pH in live rat brain.

An Extremely Inexpensive, Simple, and Flexible Carbon Fiber Electrode for Tunable Elastomeric Piezo-Resistive Sensors and Devices Realized by LSTM RNN.

Here, we describe the utility of a carbon fiber (CF) electrode that is inexpensive, simple, and flexible and can be embedded with elastomeric nanocomposite piezo-resistive sensors fabricated from silicone rubber (Ecoflex) blended with carbon nanotubes (CNTs) and various wt % of silicone thinner to tune the sensitivity and softness range. The performance of the CF electrode was evaluated on the basis of piezo-resistive responses from the sensors subjected to dynamic sinusoidal compressive strains at different levels and frequencies. The responses were positive-pressure effects with rate-dependent asymmetric nonlinear hysteresis characteristics. Developing a mathematical model to describe the rate-dependent asymmetric nonlinear hysteresis behavior is technically impossible; therefore, we employed artificial intelligence-based hysteresis modeling, long short-term memory recurrent neural network, to describe the hysteresis nonlinearity. The debonding strength of the CF electrode was determined in the pull-off testing and was found to be much higher than that of a copper wire electrode. The debonding mechanism was further elucidated via an in situ resistance profile. The importance of a robust conductive interface between a CF electrode and a nanocomposite was experimentally demonstrated. It was found that the inherent piezo-resistance of the CF was negligible compared with the piezo-resistance of the sensor; therefore, the signals from the sensor were free of interference. We believe CF-embedded tunable piezo-resistive sensors could be used in biomedical devices, artificial e-skins, robotic touch applications, and flexible keyboards where the required stretchability of the electrode can be introduced via an appropriate geometrical design.

Microbial water quality: Voltammetric detection of coliforms based on riboflavin–ferrocyanide redox couples

The ability to screen water for the presence of faecal contamination is a pressing need for rural communities dependent upon local purification systems. While there are a multitude of coliform detection assays based on the activity of β-galactosidase, this report details the adaptation of a voltammetric pH sensing strategy which could offer rapid analysis. The approach exploits the bacterial metabolism of lactose via pyruvate to lactate with the subsequent decrease in pH measured by examining the peak separation of a riboflavin (sensing) – ferrocyanide (reference) couple. Disposable carbon fibre electrodes were used as in situ sensors in Escherichia coli cultures (103–107 cfu/mL) with detection times of 4 h enabling confirmation of coliform activity. The bacterial compatibility of the riboflavin–ferrocyanide system in combination with the simplicity of the detection methodology, stand in marked contrast to many existing coliform assays and could open new avenues through which voltammetric pH sensing could be employed.

Flexible polyaniline/reduced graphene oxide/carbon fiber composites applied as electrodes for supercapacitors

Electrochemical supercapacitor (EC) is a kind of device able to generate and store clean energy, which makes it the object of intense research. This work proposes a double layer capacitance combination of electrochemical reduced graphene oxide (rGO) and carbon fiber (CF) in addition to pseudocapacitive behavior of polyaniline (PAni) to produce PAni/rGO/CF ternary composite with high capacitive response. rGO/CF and PAni/rGO/CF are obtained by electrochemical methodology. The morphological and structural analyses by scanning electron microscopy, X-ray diffraction, and Raman spectroscopy show that these nanostructured composite materials can be produced successfully. rGO/CF and PAni/rGO/CF samples are evaluated electrochemically by cyclic voltammetry (CV), electrochemical impedance spectroscopy, and charge/discharge tests. PAni/rGO/CF ternary composite presents a better performance in terms of specific capacitance and electrochemical reversibility than that of rGO/CF composite and CF electrodes. The results show that this ternary composite can be a promising electrode for applications in supercapacitors.

Energy generation by membraneless microfluidic fuel cell using acidic wastewater as a fuel

ABSTRACT A simple and novel membraneless paper-based microfluidic fuel cell was presented in this study. The occurrence of laminar flow was employed to ensure no mixing of the fuel and oxidant fluids along the bath of reaction. The acidic wastewater was used as a fuel. It was an air-breathing cell, so air and tab water were used as oxidants. Both the fuel and tab water flowed continuously under gravity. Whatman filter paper was used for preparation of the fuel cell channel and two carbon fibre electrodes were used and firmed on the edges of the cell. The performance of the cell was examined over three consecutive days. The results indicated that the present cell has the potential to generate electric power, but an extensive study is required to harvest better results. Also, the effect of carbon fibres used as electrodes in the cell was investigated.

Using Electropolymerization-based Doping for the Electro-addressable Functionalization of a Multi-electrode Array Probe for Nucleic Acid Detection.

Even though large number of individually addressable electrodes can be effectively assembled in a small area, electrochemical detection methods have a relatively limited ability to detect multiple analytes compared to microdialysis probes and other analytic techniques. Here, we report a facile method for the electro-addressable functionalization of a probe comprising of closely spaced three individually addressable carbon fiber electrodes (CFEs) for the detection of nucleic acids. First, a multi electrode array probe comprising three adjacent CFEs was fabricated through pulling a three-barrel glass capillary with a single carbon fiber in each barrel. Second, electropolymerization based doping was used for the electro-addressable functionalization of the multi-electrode array probe. To demonstrate that the current strategy works, anti-miR-34a was electrografted on only one of three electrodes by the electropolymerization of pyrrole on a specific electrode. A second electrode was coated only with polypyrrole (PPy) and the third was left unmodified. The results demonstrate that the present strategy has great potential for constructing multiplex nucleic acid micro/nano biosensors for local and in situ detection of multiple nucleic acid molecules, such as miRNAs at a time.

A high-density carbon fiber neural recording array technology

Objective. Microwire and Utah-style neural recording arrays are the predominant devices used for cortical neural recording, but the implanted electrodes cause a significant adverse biological response and suffer from well-studied performance degradation. Recent work has demonstrated that carbon fiber electrodes do not elicit this same adverse response, but these existing designs are not practically scalable to hundreds or thousands of recording sites. We present technology that overcomes these issues while additionally providing fine electrode pitch for spatial oversampling. Approach. We present a 32-channel carbon fiber monofilament-based intracortical neural recording array fabricated through a combination of bulk silicon microfabrication processing and microassembly. This device represents the first truly two-dimensional carbon fiber neural recording array. The density, channel count, and size scale of this array are enabled by an out-of-plane microassembly technique in which individual fibers are inserted through metallized and isotropically conductive adhesive-filled holes in an oxide-passivated microfabricated silicon substrate. Main results. Five-micron diameter fibers are spaced at a pitch of 38 microns, four times denser than state of the art one-dimensional arrays. The fine diameter of the carbon fibers affords both minimal cross-section and nearly three orders of magnitude greater lateral compliance than standard tungsten microwires. Typical impedances are on the order of hundreds of kiloohms, and successful in vivo recording is demonstrated in the motor cortex of a rat. 22 total units are recorded on 20 channels, with unit SNR ranging from 1.4 to 8.0. Significance. This is the highest density microwire-style electrode array to date, and this fabrication technique is scalable to a larger number of electrodes and allows for the potential future integration of microelectronics. Large-scale carbon fiber neural recording arrays are a promising technology for reducing the inflammatory response and increasing the information density, particularly in neural recording applications where microwire arrays are already used.

Bioelectrocatalytic Electrodes Modified with PQQ‐Glucose Dehydrogenase‐Calmodulin Chimera Switchable by Peptide Signals: Pathway to Generic Bioelectronic Systems Controlled by Biomolecular Inputs

AbstractConstruction of artificial allosteric protein switches is one of the central goals of synthetic biology that holds promise to transform the way we detect and quantify substances in vitro and in vivo. An artificial chimeric fusion protein of pyrroloquinoline quinone‐dependent glucose dehydrogenase with calmodulin (PQQ‐GDH‐CaM) was covalently attached to graphene nanosheets produced electrochemically on a carbon fiber electrode. The chimeric PQQ‐GDH‐CaM represents an artificial allosteric switch activated by association of a calmodulin‐binding peptide with the Ca2+‐bound calmodulin domain. The activity of the immobilized enzyme was switched between active and inactive states by adding/removing the activating peptide. The peptide‐signal switchable features originated from the enzyme 3D‐structural variations induced by the conformational (folding/unfolding) changes in the connected calmodulin unit upon formation/dissociation of its complex with the specific peptide. The peptide‐activated immobilized PQQ‐GDH‐CaM enzyme displayed direct (non‐mediated) electron transfer to the conducting electrode support upon glucose oxidation. On the contrary, in the absence of the peptide, the inactive form of the enzyme demonstrated very low bioelectrocatalytic activity for glucose oxidation. Since the conformational changes of the PQQ‐GDH‐CaM depend on the presence of Ca2+ cations and the calmodulin‐binding peptide, both of them were used as input signals to control the enzyme activity mimicking a Boolean AND logic gate. The switchable behavior of the enzyme‐modified electrode was studied electrochemically and used to assemble a signal‐switchable biofuel cell. The use of the peptide as the signaling messenger enables the design of generalizable bioelectronic systems controlled by native and synthetic biochemical signaling systems.

Carbon-Fiber Based Microelectrode Array Embedded with a Biodegradable Silk Support for In Vivo Neural Recording.

BackgroundRecently, carbon fibers have been utilized to develop a depth-type microelectrode array for chronic neural recording. Since the diameter of carbon fibers is smaller than the conventional electrodes made of metal wires or microfabricated silicon, the carbon fiber electrodes showed an improved capability for chronic neural recording with less tissue damages. However, the carbon fiber based microelectrodes have a limitation of short insertion depth due to a low stiffness.MethodsWe proposed a carbon fiber based microelectrode array embedded with a mechanical support structure to facilitate the penetration into the deeper brain. The support is made of biodegradable silk fibroin to reduce the reactive tissue responses. The 4-channel carbon fiber based microelectrode arrays were fabricated and accessed in terms of electrochemical impedance, recording capability for 1-month implantation in rat hippocampi. The electrodes with tungsten supports were fabricated and tested as a control group. Immunohistochemical analysis was performed to identify the reactive glial responses.ResultsThe carbon fiber based electrode arrays with silk supports showed about 2-fold impedance increase 2 weeks after implantation while the number of active electrodes decreased simultaneously. However, after 1 month, the electrode impedance decreased back to its initial value and the percentage of active electrodes also increased above 70%. Immunohistochemical staining clearly showed that the electrodes with silk supports induced less reactive glial responses than that with tungsten supports.ConclusionThe proposed carbon fiber based microelectrode array is expected to be used for long-term in vivo neural recording from deep brain regions with the minimized reactive tissue response.

Highly conductive electrocatalytic gold nanoparticle-assembled carbon fiber electrode for high-performance glucose-based biofuel cells

Au nanoparticle-coated highly conductive carbon fiber electrodes for high-power glucose-biofuel cells were developed based on a layer-by-layer assembling method.

Activation of carbon fiber for enhancing electrochemical performance

Carbon fiber sequentially undergoes thermal activation, electrochemical oxidation activation, electrochemical reduction activation and a secondary thermal activation process to form a highly activated carbon fiber electrode material.

Intracortical Neural Stimulation With Untethered, Ultrasmall Carbon Fiber Electrodes Mediated by the Photoelectric Effect.

Neural stimulation with tethered, electrically activated probes is damaging to neural tissue and lacks good spatial selectivity and stable chronic performance. The photoelectric effect, which converts incident light into electric potential and heat, provides an opportunity for a tetherless stimulation method. We propose a novel stimulation paradigm that relies on the photoelectric effect to stimulate neurons around a free-floating, ultrasmall (7-8μm diameter) carbon fiber probe. A two-photon microscope induced photo-stimulation with a near-infrared laser. Chronoamperometry and chronopotentiometry were used to characterize the electrochemical properties of photo-stimulation, while the fluorescence of Rhodamine-B was used to quantify temperature changes. Photo-stimulation caused a local cathodic potential pulse with minimal leakage current. Stimulation induced voltage deflections of 0.05-0.4V in vitro, varying linearly with the power of the laser source (5-40 mW). Temperature increases in the immediate vicinity of the electrode were limited to 2.5 °C, suggesting that this stimulation modality can be used without inducing heat damage. Successful stimulation was supported in vivo by increased calcium fluorescence in local neurons at stimulation onset in a transgenic GCaMP-3 mouse model. Furthermore, cells activated by photo-stimulation were closer to the electrode than in electrical stimulation under similar conditions, indicating increased spatial precision. Our results support the hypothesis that the proposed photoelectric method for neural stimulation is effective. Photoelectric stimulation is precise and avoids the need for a potentially destructive tether, making it a promising alternative to electrical stimulation.

Investigation of Mechanical and Electrochemical Performance of Multifunctional Carbon-Fiber Reinforced Polymer Composites for Electrical Energy Storage Applications

Concept of structural supercapacitors, based on carbon fiber reinforced polymer composites, has been introduced that can act as a structural load bearing component as well as an electrical energy storing device simultaneously. This multifunctional carbon fiber reinforced structural supercapacitors are fabricated by using carbon fiber and glass fiber/filter paper as reinforcements and cross-linked polymer electrolyte as a matrix. Carbon fiber mats also simultaneously serve the role of electrodes in addition to reinforcements whereas the glass fiber mat/filter paper also acts as an insulator to avoid the short-circuiting of the carbon fiber electrodes. A polymer epoxy matrix is modified by introducing ions within the cross-linked structure in order to develop an optimized polymer electrolyte. Flexural tests of structural supercapacitor are conducted to evaluate the structural performance while charge/discharge tests are conducted to evaluate the electrochemical performance. Multifunctional structural supercapacitors are tested mechanically as well as electrochemically. A structural supercapacitor is fabricated showing simultaneously an energy density of 0.11 mWh m-3, a specific capacitance of 0.8 mF.cm-3 and a flexural modulus of 26.6 GPa simultaneously.

One-step laser direct writing of boron-doped electrolyte as all-solid-state microsupercapacitors

High specific energy microsupercapacitor (MSC) as miniature all solid-state energy storage device has attracted wide interest due to its high energy and power density, long cycle life, integrability and high safety. Here, we designed and fabricated symmetric microsupercapacitors by one-step laser direct writing of boron-doped electrolytes (B-LE). The boron-doped PVA/H2SO4 electrolyte was carbonized into interdigitated cross-linked porous carbon fiber electrodes by high energy laser irradiation. These devices can deliver a high areal capacitance of 1.57 mF cm−2 (corresponding volumetric capacitance of 3.14 F cm−3) at the current density of 0.01 mA cm−2 with 5 wt% H3BO3 loading, much higher than the devices without boron doping (0.40 mF cm−2 at the same current density). Moreover, the fabricated devices display good cycling stability with a capacitance retention of 89.27% after 3000 charge-discharge cycles. These results suggest that the one-step direct laser writing to fabricate symmetric MSC has broad applications in high energy and power storage devices for miniaturized electronics.

The firing frequency of spontaneous action potentials and their corresponding evoked exocytosis are increased in chromaffin cells of CCl4 -induced cirrhotic rats with respect to control rats.

High catecolamine plasma levels because of sympathetic nervous system over-activity contribute to cirrhosis progression. The aim of this study was to investigate whether chromaffin cells of the adrenal gland might potentiate the deleterious effect exerted by this over-activity. Electrophysiological patch-clamp and amperometric experiments with carbon-fibre electrodes were conducted in single chromaffin cells of control and CCl4 -induced cirrhotic rats. The spontaneous action potential firing frequency was increased in chromaffin cells of cirrhotic rats with respect to control rats. The exocytosis evoked by that firing was also increased. However, exocytosis elicited by ACh did not vary between control and cirrhotic rats. Exocytosis triggered by depolarizing pulses was also unchanged. Amperometric recordings confirmed the lack of increased catecholamine charge released in cirrhosis after ACh or depolarization stimuli. However, the amperometric spikes exhibited faster kinetics of release. The overall Ca2+ entry through voltage-dependent Ca2+ channels (VDCC), or in particular through Cav1 channels, did not vary between chromaffin cells of control and cirrhotic rats. The inhibition of VDCC by methionine-enkephaline or ATP was not either altered, but it was increased by adrenaline in cells of cirrhotic rats. When a cocktail composed by the three neurotransmitters was tested in order to approach a situation closer to the physiological condition, the inhibition of VDCC was similar between both types of cells. In summary, chromaffin cells of the adrenal gland might contribute to exacerbate the sympathetic nervous system over-activity in cirrhosis because of an increased exocytosis elicited by an enhanced spontaneous electrical activity.

A V2O5-nanosheets-coated hard carbon fiber fabric as high-performance anode for sodium ion battery

Hard carbon with high special capacity has been widely studied as anode for sodium ion batteries (SIBs). Its storage sodium performance still needs to be further improved. Herein, a composite electrode was synthesized through growing V2O5 nanosheet array on free-standing hard carbon fiber fabric by solvothermal reaction. The electrochemical properties of the composite electrode were significantly enhanced compared with pure hard carbon fiber electrode. The composite showed a specific capacity from 241 mA h g−1 at 50 mA g−1 to 77 mA h g−1 at 1000 mA g−1 and a good cycling ability of 184 mA h g−1 after 100 cycles at 100 mA g−1. Except good storage Na ability for V2O5 nannosheets, the improvement of electrochemical performances also benefited from and the synergistic effect from the ability of fast electron transfer of hard carbon and the toleration for Na+ insertion of V2O5 nanosheet array, as well as the inhibitory effect on solid electrolyte interface (SEI) of nanostructure. Additionally, the free-standing electrodes could also increase the energy and power density. This will push the promising hard carbon material used as SIBs anode in practical applications.

Carbon nanotube/carbon fiber electrodes via chemical vapor deposition for simultaneous determination of ascorbic acid, dopamine and uric acid

A promising and low-cost electrochemical sensor was carried out with carbon nanotube modified carbon-fiber electrodes via vapor deposition method, which improved the sensitivity and reduced the detection limit of dopamine. In virtue of various techniques, such as SEM and Raman spectroscopy, the morphological, structural and crystalline properties of composites were analyzed. Moreover, simultaneous determination of dopamine, ascorbic acid and uric acid was explored at the modified carbon fiber electrode. The presence of carbon nanotubes on the surface of carbon fiber can effectively increase the surface area and electron transfer velocity of the interaction between neurotransmitter and electrode. The good linear responses of ascorbic acid, dopamine and uric acid were obtained in the range of 25.6–2000.3 μM, 5.0–120.6 μM and 20.0–800.0 μM with detection limits (S/N = 3) of 10.0 μM, 0.03 μM and 0.6 μM, respectively. Finally, this sensor was applied to the determination of dopamine in some real sample.

Development of Separation Technologies for Environmental Remediation.

This paper introduces some studies on the development of separation technologies for environmental remediation that have been performed in my laboratory over the past 20 years. The studies are related mainly to the development of easily collectable adsorbents and eco-friendly remediation technologies to remove pollutants from contaminated environments. First, the investigation of pollution in the Songhua River in China is described because it was that research that gave me the opportunity to consider the necessity of an easily collectable adsorbent. Then, the separation methods using the modified magnetite to remove pollutants by a magnet are introduced and the development of adsorbents that can float up to the water surface after adsorption at the bottom of the water is described. Electrochemical methods to accumulate pollutants in water on a carbon fiber electrode and electro-kinetic remediation to remove pollutants in soil are also introduced.