Electrochemical Nitric Oxide Sensor Research Articles

Paper-based Electrochemical Sensor Integrated with Gold Nanoparticle-Decorated Carbon Cloth as a Working Electrode for Nitric Oxide Detection in Artificial Tears.

Nitric oxide (NO) in human tears regulates numerous ocular surface processes, such as tear generation, corneal wound healing, conjunctival vascular tone, and so forth. Any deviation from its normal concentration is linked to various ocular syndromes, including microbial keratitis, conjunctivitis, pterygium, dry eye, retinitis, glaucoma, and so forth. Therefore, precise monitoring of NO in tears can be considered as a potential biomarker for ocular diseases. Here, we report a highly sensitive and selective electrochemical NO sensor using carbon ink-based electrodes. Counter, working (WE), and reference electrodes have been designed and painted on a butter paper by using carbon ink. To improve the sensing performance, the WE has been modified with a gold nanoparticle (Au NP)-deposited carbon cloth (CC). Such a paper-based sensor demonstrated high sensitivity of ∼0.34 μA μM-1 cm-2, ultralow detection limit of ∼2.35 nM, wide linear range of 10 nM-0.4 mM, and fast response time (0.35 s). The sensor also showed excellent stability and selectivity toward the interfering agents in human body fluids. Such a low-cost, flexible paper-based sensor was employed for the detection of NO in artificial tears.

Gold Nanoparticle-Modified Tungsten Oxide Flakes as Nitric Oxide Sensor Electrodes for Fruit Quality Monitoring

Development of low-cost, handheld nitric oxide (NO) sensors is very much important due to its major role in environmental pollution, biomedical research, and food safety applications. In this study, an electrochemical NO sensor has been fabricated using gold nanoparticle (Au NP)-modified tungsten oxide (WO3) nanoflakes. WO3 nanoflakes were grown hydrothermally on fluorine doped tin oxide (FTO) substrates, and Au NPs were attached by a photoreduction method. The sensing characteristics of pristine WO3 and Au NP-coated WO3 electrodes have been studied by amperometric techniques. The sensor performance has been optimized at various Au NP loadings. The optimized sensor demonstrated a high sensitivity (∼39.37 μA cm–2 mM–1) over a wide linear range (∼10 μM to 5.78 mM) with a low detection limit (∼0.12 μM). The Au NP-coated WO3 sensing electrode demonstrated high stability. The sensor current only decreases 7.54% after 31 days of continuous measurements. The sensor also showed fast response (1.7 s) and high selectivity toward NO detection. NO detection in fruit samples (apple and orange) has been studied with the Au NP-modified WO3 electrode for fruit quality monitoring application.

Noninvasive Electrochemical Nitric Oxide Detection in Human Saliva Using Pt and TiO2 Nanoparticle Composite Electrodes

Nitric oxide (NO) plays major roles in various physiological processes, such as neurotransmission, vasodilation, blood pressure monitoring, and immune response. Precise regulation of NO concentration in our body can be measured as a potential biomarker for numerous diseases such as hypertension, diabetes, Parkinson’s disease, ischemia, and rheumatoid arthritis. In this report, an electrochemical NO sensor was fabricated using a nanocomposite material consisting of Pt and TiO2 nanoparticles (Pt-TiO2 NPs). Pt and TiO2 nanoparticles were synthesized using the sol–gel method. NO sensing measurements were carried out using a Pt-TiO2 NPs-modified glassy carbon (GC) electrode after adding various concentrations of NO. The nanoparticles-modified GC electrode demonstrated high sensitivity (∼7.81 μA mM–1cm–2) in a wide linear detection range (∼10 nM to 17.79 mM). The sensor exhibited a very low detection limit (∼2.47 nM), high stability, and excellent selectivity toward NO. NO detection using a Pt-TiO2 NPs-deposited screen-printed carbon electrode was also studied in detail. Such a highly sensitive and selective sensor has been employed for noninvasive NO detection in human saliva.

Development of an electrochemical sensor for nitric oxide based on carbon paste electrode modified with Nafion, gold nanoparticles and graphene nanoribbons

Various physiological as well as pathophysiological processes in the cardiovascular system, in the immune response or in neurotransmission depend on changes of the concentration of nitric oxide (NO). Due to the instability of this ubiquitous signal molecule in vivo and in vitro, its rapid and direct detection is necessary to obtain meaningful results. Therefore, the development of a method for the rapid electrochemical detection of nitric oxide at 0.72 V (vs. Ag/AgCl) using a carbon paste electrode, modified by drop casting, is presented. As modifying solution, a nanocomposite consisting of Nafion, graphene nanoribbons, and gold nanoparticles was prepared. The voltammetric investigations with the optimized sensor were performed at room temperature in phosphate buffer solution (0.1 M, pH 7.4) as supporting electrolyte. Based on differential pulse voltammetry measurements, the obtained results for the analytical signal showed good linear response in the range of 0.39–2.34 μM and 2.34–104.7 μM with a correlation coefficient of 0.9941 and 0.9984, respectively. For both linear ranges, the repeatability as well as the reproducibility was <5% and <10%, respectively. A concentration of 40 nM was determined for the detection limit, whereas the limit of quantification was 130 nM. In addition, the influence of physiological interferences was also investigated and resulted in negligible effects. Finally, the sensor was successfully used to measure the NO release of NO donors. Based on the results obtained, the new sensor provides a simple and fast method for a direct voltammetric determination of low nitric oxide concentrations in solutions.

CuO/Cu-MOF nanocomposite for highly sensitive detection of nitric oxide released from living cells using an electrochemical microfluidic device.

The integration of large surface area and high catalytic profiles of Cu-MOF and CuO nanoparticles isdescribed toward electrochemical sensing of nitric oxide (NO) in a microfluidic platform. The CuO/Cu-MOF nanocomposite was prepared through hydrothermal method, and its formation was confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS). The CuO/Cu-MOF nanostructured modified Au electrodes enabled electrocatalytic NO oxidation at 0.6V vs. reference electrode, demonstrating linear response over a broad concentration range of 0.03-1μM and 1-500μM with adetection limit of 7.8nM. The interference effect of organic molecules and common ions was negligible, and the sensing system demonstrated excellent stability. Finally, an electrochemical microfluidic NO sensor was developed to detect of NO released from cancer cells, which were stimulated by L-arginine. Furthermore, in the presence of Fe3+, the stressed cells produced more NO. This work offers considerable potential for its practical applications in clinical diagnostics through determination of chemical symptoms in microliter-volume biological samples. Electrochemical microfluidic NO sensor was developed for detection of NO released from cancer cells. This miniaturized device consumes less materials and provides the basis for greener analytical chemistry.

Electrochemical Nitric Oxide Sensors: Principles of Design and Characterization.

Nitric oxide (NO) is a molecule of vast physiological significance, but much remains unknown about the in vivo concentration dependence of its activity, its basal level concentrations, and how levels fluctuate in the course of certain disease states. Although electrochemical methods are best suited to real-time, continuous monitoring of NO, sensors must be appropriately modified to ensure adequate selectivity, sensitivity, sensocompatibility, and biocompatibility in challenging biological environments. Herein, we provide a critical overview of recent advances in the field of electrochemical NO sensors designed to operate in physiological milieu. Unique to this review, we have opted to highlight research efforts undertaking meticulous characterization of the sensor's analytical performance. Furthermore, we compile basic recommendations to inform future electrochemical NO sensor development and facilitate cross-comparison of proposed sensor designs.

Selective and Sensocompatible Electrochemical Nitric Oxide Sensor with a Bilaminar Design.

Macrophages mediate mammalian inflammation in part by the release of the gasotransmitter, nitric oxide (NO). Electrochemical methods represent the best means of direct, continuous measurement of NO, but monitoring continuous release from immunostimulated macrophages remains analytically challenging. Long release durations necessitate consistent sensor performance (i.e., sensitivity and selectivity for NO) in proteinaceous media. Herein, we describe the fabrication of an electrochemical sensor modified by an electropolymerized 5-amino-1-naphthol (poly(5A1N)) film in conjunction with a fluorinated xerogel topcoat. The unique combination of these membranes ensures selective detection of NO that is maintained over extended periods of use (>24 h) in biological media without performance deterioration. The hydrophobic xerogel topcoat protects the underlying NO-selective poly(5A1N) film from hydration-induced desorption. The bilaminar sensor is then readily adapted for measurement of the temporal NO-release profiles from immunostimulated macrophages.

Controlled light-induced gas phase nitric oxide release from S-nitrosothiol-doped silicone rubber films

The light induced nitric oxide (NO) release properties of S-nitroso-N-acetylpenicillamine (SNAP) and S-nitrosoglutathione (GSNO) NO donors doped within polydimethylsiloxane (PDMS) films (PDMS-SNAP and PDMS-GSNO respectively) for potential inhaled NO (iNO) applications is examined. To achieve photolytic release of gas phase NO from the PDMS-SNAP and PDMS-GSNO films, narrow-band LED light sources are employed and the NO concentration in a N2 sweep gas above the film is monitored with an electrochemical NO sensor. The NO release kinetics using LED sources with different nominal wavelengths and optical power densities are reported. The effect of the NO donor loading within the PDMS films is also examined. The NO release levels can be controlled by the LED triggered release from the NO donor-doped silicone rubber films in order to generate therapeutic levels in a sweep gas for suitable durations potentially useful for iNO therapy. Hence this work may lay the groundwork for future development of a highly portable iNO system for treatment of patients with pulmonary hypertension, hypoxemia, and cystic fibrosis.

Design and Electrochemical Study of Platinum-Based Nanomaterials for Sensitive Detection of Nitric Oxide in Biomedical Applications.

The extensive physiological and regulatory roles of nitric oxide (NO) have spurred the development of NO sensors, which are of critical importance in neuroscience and various medical applications. The development of electrochemical NO sensors is of significant importance, and has garnered a tremendous amount of attention due to their high sensitivity and selectivity, rapid response, low cost, miniaturization, and the possibility of real-time monitoring. Nanostructured platinum (Pt)-based materials have attracted considerable interest regarding their use in the design of electrochemical sensors for the detection of NO, due to their unique properties and the potential for new and innovative applications. This review focuses primarily on advances and insights into the utilization of nanostructured Pt-based electrode materials, such as nanoporous Pt, Pt and PtAu nanoparticles, PtAu nanoparticle/reduced graphene oxide (rGO), and PtW nanoparticle/rGO-ionic liquid (IL) nanocomposites, for the detection of NO. The design, fabrication, characterization, and integration of electrochemical NO sensing performance, selectivity, and durability are addressed. The attractive electrochemical properties of Pt-based nanomaterials have great potential for increasing the competitiveness of these new sensors and open up new opportunities in the creation of novel NO-sensing technologies for biological and medical applications.

Sensing nitric oxide with a carbon nanofiber paste electrode modified with a CTAB and nafion composite

We describe an electrochemical sensor for nitric oxide that was obtained by modifying the surface of a nanofiber carbon paste microelectrode with a film composed of hexadecyl trimethylammonium bromide and nafion. The modified microelectrode displays excellent catalytic activity in the electrochemical oxidation of nitric oxide. The mechanism was studied by scanning electron microscopy and cyclic voltammetry. Under optimal conditions, the oxidation peak current at a working voltage of 0.75 V (vs. SCE) is related to the concentration of nitric oxide in the 2 nM to 0.2 mM range, and the detection limit is as low as 2 nM (at an S/N ratio of 3). The sensor was successfully applied to the determination of nitric oxide released from mouse hepatocytes.

Electrochemical sensor for nitric oxide using layered films composed of a polycationic dendrimer and nickel(II) phthalocyaninetetrasulfonate deposited on a carbon fiber electrode

We have developed an electrochemical sensor for nitric oxide that is based on multi-layers of nickel(II) phthalocyaninetetrasulfonate and a polyamidoamine dendrimer assembled on the surface of a carbon-fiber microelectrode. This sensor responds to nitric oxide at a working potential of 800 mV with a sensitivity of 5.54 pA∙μM‾1 which, however, depends on the dendrimer layer position deposited on the microelectrode. The limit of detection is as low as 5.5 μM at a signal-to-noise ratio of 3. The electrode exhibits good selectivity for nitric oxide over common interferents including dopamine, nitrite, hydrogen peroxide, norepinephrine, epinephrine and ascorbic acid.

Nanomaterials-based electrochemical sensors for nitric oxide

Electrochemical sensing has been demonstrated to represent an efficient way to quantify nitric oxide (NO) in challenging physiological environments. A sensing interface based on nanomaterials opens up new opportunities and broader prospects for electrochemical NO sensors. This review (with 141 refs.) gives a general view of recent advances in the development of electrochemical sensors based on nanomaterials. It is subdivided into sections on (i) carbon derived nanomaterials (such as carbon nanotubes, graphenes, fullerenes), (ii) metal nanoparticles (including gold, platinum and other metallic nanoparticles); (iii) semiconductor metal oxide nanomaterials (including the oxides of titanium, aluminum, iron, and ruthenium); and finally (iv) nanocomposites (such as those formed from carbon nanomaterials with nanoparticles of gold, platinum, NiO or TiO2). The various strategies are discussed, and the advances of using nanomaterials and the trends in NO sensor technology are outlooked in the final section.

Application of a Nitric Oxide Sensor in Biomedicine

In the present study, we describe the biochemical properties and effects of nitric oxide (NO) in intact and dysfunctional arterial and venous endothelium. Application of the NO electrochemical sensor in vivo and in vitro in erythrocytes of healthy subjects and patients with vascular disease are reviewed. The electrochemical NO sensor device applied to human umbilical venous endothelial cells (HUVECs) and the description of others NO types of sensors are also mentioned.

Fabrication of electrochemical NO sensor based on nanostructured film and its application in drug screening

As a transcellular messenger molecule, nitric oxide (NO) is involved in many physiological and pathological processes. The accurate quantitative detection of NO in vivo is particularly important. In this work, a novel electrochemical NO sensor was fabricated via electro-polymerization of ethylenediamine (EDA) on multi-walled carbon nanotubes (MWNTs) film. The sensor combined the porous structure and good conductivity of MWNTs with the good electro-catalytic ability of p-EDA film. For the detection of NO, it has a linear range from 95nM to 11μM and the limit of detection reaches 95nM with excellent reproducibility. So it was successfully applied to monitor NO release from rat liver sample for investigating the inhibition or promotion effect of drugs including oleanolic acid (OA), baicalin and Nω-nitro-l-arginine methyl ester (l-NAME) on nitric oxide synthase (NOS). The results showed that OA could promote NO release and the amount of NO increases about 1.9 times, but baicalin and l-NAME could inhibit the release of NO and the amount of NO decreased by two-thirds and 37.5%, respectively.

Inaccuracies of nitric oxide measurement methods in biological media.

Despite growing reports on the biological action of nitric oxide (NO) as a function of NO payload, the validity of such work is often questionable due to the manner in which NO is measured and/or the solution composition in which NO is quantified. To highlight the importance of measurement technique for a given sample type, NO produced from a small-molecule NO donor (N-diazeniumdiolated l-proline, PROLI/NO) and a NO-releasing xerogel film were quantified in a number of physiological buffers and fluids, cell culture media, and bacterial broth by the Griess assay, a chemiluminescence analyzer, and an amperometric NO sensor. Despite widespread use, the Griess assay proved to be inaccurate for measuring NO in many of the media tested. In contrast, the chemiluminescence analyzer provided superb kinetic information in most buffers but was impractical for NO analysis in proteinaceous media. The electrochemical NO sensor enabled greater flexibility across the various media with potential for spatial resolution, albeit at lower than expected NO totals versus either the Griess assay or chemiluminescence. The results of this study highlight the importance of measurement strategy for accurate NO analysis and reporting NO-based biological activity.

Gold Electrode Modified with Cu-Porphyrin Derived from Cardanol as Electrochemical Sensor for Nitric Oxide

In this paper, a gold electrode modified with electropolymerized copper metalloporphyrin, synthetized from technical cashew nut shell liquid, was investigated as electrochemical sensor for detection of nitric oxide in aqueous solution. Dopamine, serotonin and nitrite were evaluated as interferents for NO detection. The metal complex was electrodeposited on a gold surface by cyclic voltammetry and the analytical curves were carried out using square-wave voltammetry technique. The porphyrin-modified electrode has higher sensitivity for NO detection than the unmodified electrode. The results suggest that the proposed electrode has potential to be applied as a sensor for NO detection, as also for the interferents - dopamine, serotonin and nitrite - since these compounds presents electrochemical responses on Au/CuPp electrode.

Electrochemical and Monte Carlo studies of self-assembled trans-[Fe(cyclam)(NCS)2]+ complex ion on gold surface as electrochemical sensor for nitric oxide

Modification of gold electrode by self-assembled trans-[Fe(cyclam)(NCS)2]+ complex ion to produce an electrochemical sensor for nitric oxide detection was investigated. Dopamine, serotonin and nitrite were examined as interferents. The synthesized complex was characterized by X-ray diffraction and by infrared spectroscopy. The modified electrode was characterized by cyclic voltammetry and by surface enhanced Raman spectroscopy, analytical curves were obtained by square wave voltammetry and Monte Carlo calculations were made to model the interaction of NO molecules with the unmodified and modified surfaces. The complex has distorted octahedron geometry with the thiocyanate groups bonded to the iron ion by the nitrogen atom and in the trans orientation. SERS spectrum and Monte Carlo calculations supported that the complex ion is adsorbed on Au surface from the Au-S bond. The electrochemical current for NO oxidation on the modified electrode was higher than that presented by the bare Au electrode and a good correlation was presented by the experimental analytical curve and the calculated Monte Carlo interaction energy versus amount NO molecules plot. The Monte Carlo calculations indicated that the higher current response for NO oxidation on the Au/trans-[Fe(cyclam)(NCS)2]+ surface was due to the stronger interaction of the NO molecules with complex adsorbed on the Au surface than the interaction of NO with the bare Au surface. The theoretical analyses also revealed that NO molecules cluster on Au surface. Dopamine, serotonin and nitrite were interferents for the detection of NO with dopamine and serotonin was less significant interferents than the nitrite. The proposed modified electrode presented good electrochemical stability, detection limit and quantification limit of 5.15×10−8molL−1 and 1.72×10−7, respectively, which were about one order of magnitude lesser than the corresponding values obtained for the bare Au electrode. The results indicated that the proposed electrode has potential to be applied as a sensor for NO detection.

Real-time evaluation of nitric oxide (NO) levels in cortical and hippocampal areas with a nanopore-based electrochemical NO sensor

Nitric oxide (NO) is an important biomolecule for regulating various brain functions, such as the control of neurovascular tone. NO, however, cannot be stored inside cells where NO is produced and immediately diffuses through the cellular membrane and decays rapidly, which makes the detection of NO extremely hard in an in vivo setting. We constructed an amperometric NO nanosensor and utilized it to directly measure NO release in the living brain. The NO nanosensor uses nanopores (pores with an opening radii <500nm) in which NO is oxidized at the porous platinum surface. The nanopore-based sensor was inserted vertically into the brains of anesthetized mice up to the end of the hippocampal CA 3 region, or to a depth of about 3mm. The sensor was slowly advanced in the brain in 0.5μm increments and in 0.05s temporal steps. Different levels of NO release were monitored by the nanopore NO sensor during the course of the penetration. The hippocampal CA3 region had the highest level of NO release, which was followed by CA2 and CA1 of the hippocampus and the cortex. The levels of NO release were not uniformly distributed within the cortical and hippocampal areas of living brain. In sum, the nanopore-based NO sensor was able to grossly measure NO contents within living brain in real time and with high sensitivity. This study may provide good insights about the relationship between the distributions of NOS-immunoreactive neurons and the directly measured levels of NO release in brain.

Study of a gold electrode modified by trans-[Ru(NH 3) 4(Ist)SO 4] + to produce an electrochemical sensor for nitric oxide

The modification of a gold electrode surface by electropolymerization of trans-[Ru(NH 3) 4(Ist)SO 4] + to produce an electrochemical sensor for nitric oxide was investigated. The influence of dopamine, serotonin and nitrite as interferents for NO detection was also examined using square-wave voltammetry (SWV). The characterization of the modified electrode was carried out by cyclic voltammetry, electrochemical quartz crystal microbalance (EQCM) and SERS techniques. The gold electrode was successfully modified by the trans-[Ru(NH 3) 4(Ist)SO 4] + complex ion using cyclic voltammetry. The experiments show that a monolayer of the film is achieved after ten voltammetric cycles, that NO in solution can coordinate to the metal present in the layer, that dopamine, serotonin and nitrite are interferents for the detection of NO, and that the response for the nitrite is much less significant than the responses for dopamine and serotonin. The proposed modified electrode has the potential to be applied as a sensor for NO.

ChemInform Abstract: Electrochemical Nitric Oxide Sensors for Physiological Measurements

AbstractReview: 63 refs.