Sensors superoxide

O2 also can be detected by cyt c-modified electrode [214], When cyt c was covalently attached to the modified electrode, the immobilized cyt c was used as an integral part of an amperometric O2 sensor. Superoxide generated by xanthine/XOD caused the one-electron reduction of cytochrome c to cytochrome c. The reduced protein was then reoxidized at the electrode surface. McNeil used this immobilization procedure to detect O2 production by stimulated human neutrophils [215]. The neutrophils that stimulated with phorbol-12 myristate-13 acetate (PMA) produced current changes that were cell number dependent. Fabian [216] used a platinized activated carbon electrode (PACE) to... 

Superoxide electrochemical sensors and biosensors principles, development and applications... 

Superoxide Electrochemical Sensors and Biosensors Principles, Development and Applications... 

J. Chen, U. Wollenberger, F. Lisdat, B. Ge, and F.W. Scheller, Superoxide sensor based on hemin modified electrode. Sens. Actuators B. 70,115—120 (2000). 

K.V. Gobi and F. Mizutani, Efficient mediatorless superoxide sensors using cytochrome c-modified electrodes. Surface nano-organization for selectivity and controlled peroxidase activity. J. Electroanal. Chem. 484, 172-181 (2000). 

V. Lvovich and A. Scheeline, Amperometric sensors for simultaneous superoxide and hydrogen peroxide detection. Anal. Chem. 69, 454-462 (1997). 

L. Campanella, L. Persi, and M. Tomassetti, A new tool for superoxide and nitric oxide radicals determination using suitable enzymatic sensors. Sens. Actuators B. 68, 351-359 (2000). 

C.J. McNeil, K.R. Greenough, P.A. Weeks, and C.H. Self, Electrochemical sensors for direct reagentless measurement of superoxide production by human neutrophils. Free Rad. Res. Comm. 17, 399-406 (1992). 

B. Ge and F. Lisdat, Superoxide sensor based on cytochrome c immobilized on mixed-thiol SAM with a new calibration method. Anal. Chim. Acta. 454, 53-64 (2002). 

M.K. Beissenhirtz, F.W. Scheller, and F. Fisdat, A superoxide sensor based on a multilayer cytochrome c electrode. Anal. Chem. 76, 4665-4671 (2004). 

K. Endo, T. Miyasaka, S. Mochizuki, N. Himi, H. Asahara, K. Tsujioka, and K. Sakai, Development of a superoxide sensor by immobilization of superoxide dismutase. Sens. Actuators B. 83, 30-34 (2002). 

J. Di, S. Bi, and M. Zhang, Third-generation superoxide anion sensor based on superoxide dismutase directly immobilized by sol-gel thin film on gold electrode. Biosen. Bioelectron. 19, 1479-1486 (2004). 

Many methods including photometric, fluorimetric, chromatographic, and electrochemical methods have been used to detect the antioxidants so far. Recently, electrochemical methods have intensively been used for antioxidant detection. Among the electrochemical methods, the detection of antioxidant based on the direct redox transformation of cyt c has been studied over the decade. Since cyt c can act as an oxidant of superoxide, the superoxide level in solution can be detected as an oxidation current at the sensor electrode due to electron transfer from the radical via cyt c to the electrode. 

The principle of antioxidant detection is shown in Fig. 17.3. Superoxide was enzymatically produced and dismutated spontaneously to oxygen and H202. Under controlled conditions of superoxide generation such as air saturation of the buffer, optimal hypoxanthine concentration (100 pM) and XOD activity (50mU ml-1) a steady-state superoxide level could be obtained for several min (580-680 s). Since these steady-state superoxide concentrations can be detected by the cyt c-modified gold electrode, the antioxidate activity can be quantified from the response of the sensor electrode by the percentage of the current decrease. 

K.V. Gobi, Y. Sato, and F. Mizutani, Mediatorless superoxide dismutase sensors using cytochrome c-modified electrodes xanthine oxidase incorporated polyion complex membrane for enhanced activity and in-vivo analysis. Electroanalysis 13, 397-403 (2001). 

Superoxide sensor Cytochrome c (cyt. c) Poly(anilinesulfonic acid) (PASA) [92, 214, 215]... 

Other detection methods have been used in optical MIP sensing systems. An MIP-based chemiluminescent flow-through sensor was developed for the detection of 1,10-phenanthroline (Lin and Yamada 2001). A metal complex was used to catalyze the decomposition of hydrogen peroxide and form the superoxide radical ion that can... 

Our research group recently approached the problem of radical determination starting from the determination of oxygen free radicals, in particular superoxide radical, and assembling several new kinds of electrochemical sensors and biosensors suitable for this purpose [21-24]. Firstly, a voltammetric system based on the detection of reduced cytochrome c this system was also applied to develop a... 

Several other chromophores have been used in the development of sensors based upon ECL. For example, the luminol reaction is a conventional chemi-luminence reaction that has been studied in detail and it is believed that the mechanism of the ECL reaction is similar, if not identical, to that of the chemiluminescence. As shown in Fig. 2, the luminol ion undergoes a one-electron oxidation to yield a diazaquinone, which then reacts with peroxide or superoxide ( OOH) to give the excited 3-aminophthalate which has an emission maximum of 425 nm. This reaction is particularly versatile and has been utilized in a variety of ECL assays, many of which have been previously summarized by Knight [1], The luminol ECL reaction can be used for the determination of any species labeled with luminol derivatives, hydrogen peroxide, and other peroxides or enzymatic reactions that produce peroxides. A couple of examples are described later. 

Relatively recently Fe/S proteins have been found to function in the regulation of biosynthesis. This can be by promoting deoxyribonucleic acid (DNA) transcription, e.g. the [2Fe-2S] containing Escherichia coli superoxide-activated (SoxR) transcription activator [10-12], or the presumably [4Fe-4S]-containing E. coli transcription factor fumarate nitrate reduction (FNR) [13,14], Alternatively, the Fe/S protein can act by interference with messenger ribonucleic acid (mRNA) translation, i.e., the iron regulatory proteins (IRPs) [15,16], These interactions are stoichiometric, therefore not catalytic. Presumably, they are also a form of sensoring, namely, of oxidants and/or iron [17],... 

This review is a survey of the research on the direct electron transfer (DET) between biomolecules and electrodes for the development of reagentless biosensors. Both the catalytic reaction of a protein or an enzyme and the coupling with further reaction have been used analytically. For better understanding and a better overview, this chapter begins with a description of electron transfer processes of redox proteins at electrodes. Then the behaviour of the relevant proteins and enzymes at electrodes is briefly characterized and the respective biosensors are described. In the last section sensors for superoxide, nitric oxide and peroxide are presented. These have been developed with several proteins and enzymes. The review is far from complete, for example, the large class of iron-sulfur proteins has hardly been touched. Here the interested reader may consult recent reviews and work cited therein [1,19]. 

In most cases superoxide anion sensors contain C3dochrome c in direct contact to gold electrodes, where c5dochrome c is covalently coupled to succinimide activated surface modifiers (DSP and DTSSP, respectively), MPA/MP or MUA/MU (Table 2.5). 

SOD-modified sensors also were demonstrated to respond to superoxide addition. Using either 3-mercaptopropionic acid [68] or cysteine [70] as a promoter on Au-electrodes superoxide sensors could be constructed where FeSOD and CuZnSOD in direct contact to the electrode acts as catalyst for the highly specific dismutation of O2 to O2 and H2O2. Either Fe or Cu of SOD are oxidized and reduced (Fe /Fe Cu°/Cu ) at the modified gold electrodes. Both, anodic and cathodic peak currents increase in the presence of O2. At a potential of 300 or- 200 mV O2 -generation could be recognized with detection limits of 5 and 6 nM, respectively [70]. 

---