In vivo nitric oxide sensor using non-conducting polymer-modified carbon fiber (original) (raw)
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Biosensors & Bioelectronics, 2008
The measurement of Nitric oxide ( • NO) in real-time has been a major concern due to the involvement of this ubiquitous free radical modulator in several physiological and pathological pathways in tissues. Here we performed a study aiming at evaluating different types of carbon fibers, namely Textron, Amoco, Courtaulds and carbon nanotubes (University of Kentucky) covered with Nafion ® /o-phenylenediamine (o-PD) for • NO measurement in terms of sensitivity, LOD, response time and selectivity against major potential interferents in the brain (ascorbate, nitrite and dopamine). The results indicate that, as compared with the other carbon fibers and nanotubes, Textron carbon fiber microelectrodes coated with two layers of Nafion ® and o-PD exhibited better characteristics for • NO measurement as they are highly selective against ascorbate (>30,000:1), nitrite (>2000:1) and dopamine (>80:1). These coated Textron microelectrodes showed an average sensitivity of 341 ± 120 pA/M and a detection limit of 16 ± 11 nM. The better performance of the Textron fibers is likely related to a stronger adhesion or more uniform coating of the Nafion ® and o-PD polymers to the fiber surface. In addition, the background current of the Textron carbon fibers is low, contributing to the excellent signal-to-noise for detection of • NO.
Journal of Electroanalytical Chemistry, 1997
An NO sensor based on a carbon fibre microelectrode modified by a poly(N-methylpyrrole) incorporating [(H20)FeUlpwt iO39 ]4sublayer and coated by a Nation ® external layer is described. It is based on the NO oxidation current measured by differential normal pulse voltammetry. In solution, a linear response is obtained between this oxidation current and the NO concentration in the range 10-7 to 10-3 M with a sensitivity of 2.65 + 0.15 nA lzM-i. A comparative study has been carried out with poly(N-methylpyrrole) doped with 004, polypyrrole doped with sulfonated nickel porphyrin, polypyrrole and poly(N-methylpyrrole) doped with Nation ®. This sensor implanted in the rat brain is efficient to detect in real time the NO released. The validation of in vivo measurements is made by injecting the rat with an NO-synthase inhibitor.
Analytica Chimica Acta, 2005
The role of nitric oxide ( • NO) as a regulatory diffusible molecule in the brain requires the evaluation of its concentration dynamics. In this work, we have developed microelectrodes suitable for real time electrochemical measurements of • NO in vitro. Nafion and o-phenylenediamine were used to modify the surface of carbon fiber microelectrodes (8 m diameter; ≈100 m tip length). Coating with Nafion was done at 170 • C and the o-phenylenediamine solution was electropolimerized on the carbon surface. • NO peak potential (+0.78 ± 0.03 V versus Ag/AgCl) was determined by square wave voltammetry with • NO solutions prepared from the-generating compound diethylenetriamine/nitric oxide (DETA/NO). Microelectrodes were calibrated by amperometry at a potential of +0.90 V versus Ag/AgCl. They showed good sensitivity (954 ± 217 pA/M; n = 6) and linearity to • NO in the concentration range of 100-1000 nM. They were also characterized in terms of detection limit (6 ± 2 nM, n = 4), response time at 50% (1 s), and selectivity against interferents, such as nitrite (780 ± 84:1, n = 6), ascorbic acid (750 ± 187:1, n = 6) or dopamine (18 ± 2:1, n = 6). Injections of 1 mM l-glutamate, 1 mM l-arginine, and 0.1 mM N-methyl-d-aspartate did not produce changes in background current. Finally, the microelectrodes were used to measure • NO concentration dynamics in rat hippocampal brain slices stimulated with l-glutamate and N-methyl-d-aspartate. Taken together, the data indicate that the microelectrodes exhibit the proper sensitivity and selectivity for studies of • NO dynamics in brain slices (in vitro) and possibly in whole brain (in vivo) recordings.
Biosensors and Bioelectronics, 2008
A nitric oxide (NO) microbiosensor based on cytochrome c (cyt c), a heme protein, immobilized onto a functionalized-conducting polymer (poly-TTCA) layer has been fabricated for the in vivo measurement of NO release stimulated by an abuse drug cocaine. Based on the direct electron transfer of cyt c, determination of NO with the cyt c-bonded poly-TTCA electrode was studied using cyclic voltammetry and chronoamperometry. Interferences for the sensory of NO by foreign species such as oxygen and hydrogen peroxide were minimized by covering a Nafion film on the modified electrode surface. Cyclic voltammograms taken using the cyt c/poly-TTCA electrode with NO solutions show a reduction peak at −0.7 V. The calibration plot showed the hydrodynamic range of 2.4-55.0 M. The detection limit was determined to be 13 ± 3 nM based on S/N = 3. The microbiosensor was applied into the rat brain to test fluctuation of NO evoked by the abuse drug cocaine. The concentrations of NO levels by acute and repeated injections of cocaine were determined to be 1.13 ± 0.03 and 2.13 ± 0.05 M, respectively, showing high sensitivity of the microbiosensor in monitoring NO concentrations in the in vivo intact brain.
Electrochemical nitric oxide sensors for physiological measurements
Chemical Society Reviews, 2010
The important biological roles of nitric oxide (NO) have prompted the development of analytical techniques capable of sensitive and selective detection of NO. Electrochemical sensing, more than any other NO detection method, embodies the parameters necessary for quantifying NO in challenging physiological environments such as blood and the brain. In this tutorial review, we provide a broad overview of the field of electrochemical NO sensors, including design, fabrication, and analytical performance characteristics. Both electrochemical sensors and biological applications are detailed. Mark Schoenfisch (left) is a Professor of Chemistry in the Department of Chemistry at the University of North Carolina at Chapel Hill (UNC-Chapel Hill). Dr Schoenfisch earned undergraduate degrees in Chemistry (BA) and Germanic Languages and Literature (BA) at the University of Kansas prior to attending the University of Arizona for graduate studies in Chemistry (PhD). Before starting at UNC-Chapel Hill, he spent two years as a National Institutes of Health Postdoctoral Fellow at the University of Michigan. His research interests span biomaterials, chemical sensors, nitric oxide release scaffolds, and scanning probe microscopy. Benjamin J. Privett (right) earned a BS in Chemistry from Centre College in 2005 where he conducted research on the development of catalysts for the destruction of toxic ink components. Prior to graduate school, he was an NSF REU participant at the University of Idaho. He is currently a graduate student in the laboratory of Dr Mark Schoenfisch at the University of North Carolina at Chapel Hill. His doctoral research involves the development of sol-gel-derived sensors for the detection of sepsis.
Biosensors and Bioelectronics, 2013
A novel biomimetic microsensor for measuring nitric oxide (NO) in the brain in vivo was developed. The sensor consists of hemin and functionalized multi-wall carbon nanotubes covalently attached to chitosan via the carbodiimide crosslinker EDC followed by chitosan electrodeposition on the surface of carbon fiber microelectrodes. Cyclic voltammetry supported direct electron transfer from the Fe III /Fe II couple of hemin to the carbon surface at À 0.370 V and À 0.305 V vs. Ag/AgCl for cathodic and anodic peaks, respectively. Square wave voltammetry revealed a NO reduction peak at À 0.762 V vs. Ag/AgCl that increased linearly with NO concentration between 0.25 and 1 mM. The average sensitivity of the microsensors was 1.72 nA/mM and the limit of detection was 25 nM. Oxygen and hydrogen peroxide reduction peaks were observed at À 0.269 V and À 0.332 V vs. Ag/AgCl, respectively and no response was observed for other relevant interferents, namely ascorbate, nitrite and dopamine. The microsensor was successfully applied to the measurement of exogenously applied NO in the rat brain in vivo.
Evaluation of basic performance and applicability of a newly developed in vivo nitric oxide sensor
Physiological Measurement, 2002
Direct measurement of nitric oxide (NO) is of great importance and value for both in vitro and in vivo studies on dynamic NO bioactivity. Here, we evaluated the basic performance of a newly developed NO sensor (Innovative Instruments, Inc.). Unlike other NO sensors, the new NO sensor has a highly durable, gas-permeable coating and is affected much less by electrical interference due to its integrated structure where working and reference electrodes are combined in a single element. Calibration with NO gas showed high sensitivity of about 580 pA per nmol-NO l −1 (the detection limit 0.08 nmol-NO l −1 , S/N = 3). This sensor also showed high selectivity (25 000 times and more) to NO, compared with NO-related reagents such as L-arginine, N G -monomethyl-L-arginine, acetylcholine, nitroglycerin (NTG) and tetrahydrobiopterin as well as dissolved oxygen. As an in vivo application, the sensor was located in the anaesthetized rat abdominal aorta to measure NTG-derived plasma NO. Intra-aortic infusion of 0.5 mg NTG caused a measurable increase in plasma NO level (2.0 ± 2.2 nmol l −1 , mean ±SD, n = 3). In conclusion, the new NO sensor demonstrated a satisfying performance for both in vitro and in vivo applications.
The Utility of the Nitric Oxide Electrochemical Sensor in Biomedical Research
Sensors, 2003
In recent years World Precision Instruments Inc. (WPI) produced for commercial use a selective and sensitive electrochemical sensor for the detection of the important biological free radical nitric oxide (NO). Though many kinds of NO sensors are now commercially available WPI offers a range of sensors of variable size and applicability for the detection of NO in vivo and in in vitro biomedical samples. This article overviews the working characteristics of the sensors and their utility for biomedical research.
Analytica Chimica Acta, 2015
A highly sensitive amperometric gas-phase nitric oxide (NO) sensor based on a Pt working electrode chemically deposited on a Nafion film is described. The Pt electrode is chemically deposited on a Nafion 117 membrane by impregnating the film with Pt(NH 3 ) 4 2+ ions, which are then exposed to NaBH 4 to precipitate conductive Pt metal. The sensor was characterized with a mass-flow controlled 1 ppm NO standard gas and has an electrochemical surface area of 34 ± 9 cm 2 , low limits of detection (4.3 ± 1.1 ppb) and a fast response time (<5s) toward changes in gas phase NO levels. Good correlation was found for measurements with the new amperometric Pt-Nafion sensor vs. chemiluminescence results for detecting the rates of NO released from CarboSil 2080A polymer films doped with S-nitroso-N-acetylpenicillamine (R = 0.999, m = 0.999, n = 6) and for electrochemical reduction of nitrite to NO (R = 0.999, m = 0.938, n = 3) mediated by a copper(II)-tri(2-pyridylmethyl)amine complex.
Talanta, 2008
The development of reliable in vivo chemical sensors for real-time clinical monitoring of blood gases, electrolytes, glucose, etc. in critically ill and diabetic patients remains a great challenge owing to inherent biocompatibility problems that can cause errant analytical results upon sensor implantation (e.g., cell adhesion, thrombosis, inflammation). Nitric oxide (NO) is a well-known inhibitor of platelet activation and adhesion, and also a potent inhibitor of smooth muscle cell proliferation. In addition, NO mediates inflammatory response and promotes angiogenesis. Polymers that release or generate NO at their surfaces have been shown to exhibit greatly enhanced thromboresistance in vivo when in contact with flowing blood, as well as reduce inflammatory response when placed subcutaneously, and thus have the potential to improve the biocompatibility of implanted chemical sensors. Locally elevated NO levels at the surface of implanted devices can be achieved by using polymers that...