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Amperometric analysis of NO in real samples using a GC–Au nanocomposite (1-layer) electrode (a), where each step corresponds to the addition of 200 m l of liver extract, and (b) each step corresponds to the addition of 200 m l of the ointment solution, and (c) each step corresponds to the addition of 200 m l of the PBMC extract; applied potential 1⁄4 À 0.24 V.
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An electrochemical assay for sensing NO in biological systems is described in this paper. The ferrocene mediated reduction of NO, facilitated by the gold nanocomposite modified glassy carbon electrode is followed by an amperometric procedure. The analytical protocol involves the modification of a glassy carbon electrode by an overlayer of Au nanoco...
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Context 1
... of NO in biological samples NO in liver extract. A solution of liver extract was prepared as described in the experimental section and NO content was analyzed by amperometry and arginine was added before the analysis. Fig. 6a represents the amperometric curve for different additions of liver extract and the inset depicts the linear rela- tionship between the NO generated and the reduction current. NO in PBMCs (peripheral blood mononuclear cells). Peripheral blood mononuclear cells (PBMCs) which constitute a very important part of our peripheral immune ...
Context 2
... mination of NO is of importance for studying the content of NO under stress and free conditions and also for studying the harmful effects of overproduction of NO. Current literature reports make use of the Griess assay for the determination of NO. In this work we have explored the possibility of determining NO using our experimental protocol. Fig. 6c shows the amper- ometric curve obtained for different additions of PBMCs. In the inset it can be observed that the amount of NO present in the PBMCs varies linearly with the observed amperometric reduc- tion ...
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Citations
... Metal nanomaterials (NMs), especially noble metal (Au and Pt) NMs, have been used in electrochemical sensors due to their unique electrochemical, electronic, and catalytic properties. Varatharajan and co-workers have demonstrated that the combination of gold nanocomposites and hydroxypropyl-βcyclodextrin encapsulated soluble ferrocene significantly improves the sensitivity of the estimation of NO in biological systems including peripheral blood mononuclear cells [134]. Duan's group reported a new type of flexible electrochemical biosensor based on graphene paper loaded with closely packed Au@Pt core-shell nanoparticles as a freestanding cell culture substrate that was used for the real-time monitoring of NO cell secretions [135]. ...
The incorporation of nanomaterials into electrochemical sensors is an attractive approach towards the improvement of the sensitivity of amperometry and also can provide improved sensor selectivity and stability. This review (with 137 references) details the current state of the art and new trends in nanomaterial-based electrochemical sensing of hydrogen peroxide (H2O2), hydrogen sulfide (H2S) and nitric oxide (NO) in cells or released by cells. The article starts with a discussion of the significance of the three analytes, and this is followed by three sections that summarize the electrochemical detection schemes for H2O2, H2S and NO. Each section first summarizes the respective physiological roles, and then reviews electrochemical sensors based on the use of carbon nanomaterials, noble metal nanomaterials, metal oxide nanomaterials, and layered doubled hydroxides. The materials are compiled in three tables along with figures of merit for the various sensors.
free download:http://www.springer.com/home?SGWID=0-0-1003-0-0&aqId=3261739&download=1&checkval=82455b7860d6f54719e59e1a9575bdc2
... Metal nanomaterials (NMs), especially noble metal (Au and Pt) NMs, have been used in electrochemical sensors due to their unique electrochemical, electronic, and catalytic properties. Varatharajan and co-workers have demonstrated that the combination of gold nanocomposites and hydroxypropyl-βcyclodextrin encapsulated soluble ferrocene significantly improves the sensitivity of the estimation of NO in biological systems including peripheral blood mononuclear cells [134]. Duan's group reported a new type of flexible electrochemical biosensor based on graphene paper loaded with closely packed Au@Pt core-shell nanoparticles as a freestanding cell culture substrate that was used for the real-time monitoring of NO cell secretions [135]. ...
... We have identified ferrocene as a suitable mediator for the reduction of NO at low over potentials in our earlier work and we have demonstrated the analytical utility of the reaction for the detection of NO by electrochemical and spectrophotometric techniques [11][12][13]. In the present work, we have attempted to covalently tether the mediator ferrocene to the gold electrode surface through a self-assembled monolayer and demonstrated a reagent less detection of NO up to nanomolar levels. ...
An amperometric nitric oxide (NO) sensor based on a ferrocenemethanolfunctionalized electrode was fabricated. The sensor could work at low over potential with a detection limit of 50 nM. The sensor exhibited excellent analytical performance, including a NO sensitivity of 6 μA nM−1 cm−2. The surface coverage of ferrocence on the modified electrode was calculated to be 2.06 × 10−10 mol cm−2. The heterogeneous rate constant calculated for ferrocene mediated NO reduction was found to be 3.5 × 105 cm3 mol−1 s−1. Further, the blue colored intermediate (Ferrocene hyponitrite) obtained during chemical and electrochemical reduction of NO mediated by ferrocene was isolated and characterized spectroscopically. Nitrous oxide (N2O), the final product of electrochemical reduction of NO was characterized using GC-MS. The mechanism of ferrocene-mediated nitric oxide reduction was found to be similar to biological NO reduction exhibited by the enzymes.
Our research demonstrates the effectiveness of fluorescence quenching between polyethyleneimine functionalised carbon dots (PEI-CDs) and cyclodextrin encapsulated ferrocene for fluorogenic detection of nitric oxide (NO). We confirmed that ferrocene can be used as a NO probe by observing its ability to quench the fluorescence emitted from PEI-CDs, with NO concentrations ranging from 1 × 10–6 M to 5 × 10–4 M. The photoluminescence intensity (PL) of PEI-CDs decreased linearly, with a detection limit of 500 nM. Previous studies have shown that ferrocene is a selective probe for NO detection in biological systems by electrochemical and colorimetric methods. The addition of fluorogenic NO detection using ferrocene as a probe enables the development of a three-way sensor probe for NO. Furthermore, the triple mode NO detection (electrochemical, colorimetric, and fluorogenic) with ferrocene aids in processing sensing data in a controlled manner similar to Boolean logic operations. This work presents key findings on the mechanism of fluorescence quenching between ferrocene hyponitrite intermediate and PEI-CDs, the potential of using ferrocene for triple channel NO detection as a single molecular entity, and the application of logic gates for NO sensing.
Nitric oxide (NO) signaling plays many pivotal roles impacting almost every organ function in mammalian physiology, most notably in cardiovascular homeostasis, inflammation, and neurological regulation. Consequently, the ability to make real-time and continuous measurements of NO is a prerequisite research tool to understand fundamental biology in health and disease. Despite considerable success in the electrochemical sensing of NO, challenges remain to optimize rapid and highly sensitive detection, without interference from other species, in both cultured cells and in vivo. Achieving these goals depends on the choice of electrode material and the electrode surface modification, with graphene nanostructures recently reported to enhance the electrocatalytic detection of NO. Due to its single-atom thickness, high specific surface area, and highest electron mobility, graphene holds promise for electrochemical sensing of NO with unprecedented sensitivity and specificity even at sub-nanomolar concentrations. The non-covalent functionalization of graphene through supermolecular interactions, including π–π stacking and electrostatic interaction, facilitates the successful immobilization of other high electrolytic materials and heme biomolecules on graphene while maintaining the structural integrity and morphology of graphene sheets. Such nanocomposites have been optimized for the highly sensitive and specific detection of NO under physiologically relevant conditions. In this review, we examine the building blocks of these graphene-based electrochemical sensors, including the conjugation of different electrolytic materials and biomolecules on graphene, and sensing mechanisms, by reflecting on the recent developments in materials and engineering for real-time detection of NO in biological systems.
In this study, a new Schiff base of bis-N-(2-mercaptophenyl) salicylaldimine (MPSI) has been immobilized on a bare gold electrode as a novel self assembled monolayer (SAM) sensor for determination of promethazine hydrochloride (PMZ). Cyclic voltammetry and electrochemical impedance spectroscopy are used to study the properties of monolayer of Schiff's base on a gold electrode (MPSI-Au SAM electrode) using the [Fe(CN)6]3 −/4 − probe. Also, the characterization of the MPSI-Au electrode was performed by scanning electron (SEM) and atomic force microscopy (AFM). The electrochemical behavior of PMZ on the MPSI-Au SAM electrode was studied by several voltammetry methods in phosphate buffer solution as supporting electrolyte. The modified electrode showed good selectivity in the presence of interference of ascorbic and uric acid. A calibration curve was obtained for PMZ in a linear range of 1.0–240.0 μmol L− 1. The detection limit for promethazine hydrochloride was found to be 24.6 nmol L− 1. The results indicated that the MPSI-Au SAM electrode could be employed for the determination of promethazine hydrochloride in urine and plasma samples.
Nitric oxide (NO) is a ubiquitous signaling molecule, which takes an important part in various complicated physiological process, such as neurotransmission, energy metabolism, immune response, inflammatory response and tumorigenesis. Therefore, the detection of NO is of great significance. The conventional methods of NO detection are not able to determine NO level in vivo at a real-time scale and the application of these methods are frequently restricted. In this review, we focus on the development of copper (II) compound-derived NO fluorescent probes that have been comprehensively used for the determination of NO level in the cultured cells and in vivo.
A fluorescence sensor for nitric oxide (NO) was realized by covalently immobilizing reduced fluoresceinamine molecules onto the surface of siliconnanowires (SiNWs). The fluorescence intensity of the sensor can be greatly enhanced by NO. The sensor exhibits excellent selectivity for NO against other reactive species. Facile synthesis, nontoxicity, rapid response and use in a 100% aqueous solution endows the present sensor with suitability for biosystems. As an application, the sensor was used to detect NO released from liver extract, and exhibited high sensitivity and selectivity as well as rapid response. The fluorescence image from a single SiNW-based sensor showed a fine spatial resolution. The present sensor paves a way to detect NO at specific location in a single cell by inserting a single SiNW-based sensor into the cell.
An unprecedented straightforward approach wherein an excess of diisobutylaluminum hydride is able to strip off in reasonable yield (45%) and in a regioselective manner four methyl groups from permethylated α-cyclodextrin, to provide a symmetric tetrol (2) in one chemical step from a commercially available material is described. An asymmetric tetrol (3) was also isolated from the reaction as a minor product (19%). Both compounds are unambiguously characterized by 1H NMR, 13C NMR, COSY, HSQC and HRMS.
