Chemiluminescence of lucigenin by electrogenerated superoxide ions in aqueous solutions

Abstract

The chemiluminescence reaction of lucigenin (Luc(2+)c2NO(3) (-), N,N'-dimethyl-9,9'-biacridinium dinitrate) at gold electrodes in dioxygen-saturated alkaline aqueous solutions (pH 10) was investigated in detail by the use of electrochemical emission spectroscopy. We noted that both O(2) and Luc(2+) are reduced on a gold electrode in aqueous solution of pH 10 in almost the same potential region. From this fact, we expected chemiluminescence based on a radical-radical coupling reaction of superoxide ion (O(2).(-)) and one-electron reduced form of Luc(2+) (Luc.(+), a radical cation). Chemiluminescence was actually observed in the potential range where O(2) and Luc(2+) were simultaneously reduced at the electrodes. The effects were examined upon addition of enzymes, i.e. superoxide dismutase (SOD) and catalase, into the solution and the substitution of heavy water (D(2)O) for light water (H(2)O) as a solvent on the chemiluminescence. In the presence of native and active SOD, chemiluminescence was completely absent. On the other hand, chemiluminescence was observed, unchanged in the presence of either denatured and inert SOD or catalase. In addition, the amount of chemiluminescence in D(2)O solution was about three times greater than that in H(2)O solution. These results, together with cyclic voltammetric results, suggest that O(2).(-) participates directly in the chemiluminescence but H(2)O(2) does not, and the chemiluminescence results from the coupling reaction between O(2).(-) and Luc(.+) under the present experimental conditions. These chemically unstable species, O(2).(-) and Luc.(+), are produced during the simultaneous electroreduction of O(2) and Luc(2+). The coupling reaction between those radical species would lead to the formation of a dioxetane-type intermediate and, finally, to chemiluminescence. The chemiluminescence reaction mechanism is discussed.

Application of Electrochemiluminescence for the Evaluation of the Antioxidant Capacity of Some Phenolic Compounds Against Superoxide Anion Radicals

“…452 nm (reaction 4). [13][14][15][16] It is worthy of note that the ECL spectrum with a broad band at 510 nm was observed in our experiment, which suggested that the light emission originated from the excited triplet state *Luc 2+ through the energy-transfer process from *NMA to Luc 2+ , which fluoresced at longer wavelengths at 510 nm. The ECL reaction scheme for the Luc 2+ /O2 system is summarized in Fig.…”

“…In the cathodic process, the coupling reaction between an in situ electrogenerated radical species, such as one-electron reduced lucigenin (Luc· + ) and O2· -, would lead to the formation of a dioxetane-type intermediate, and finally, to generate chemiluminescence in neutral or relatively weak alkaline solutions (pH 7 -10). [13][14][15][16] Lucigenin ECL has been used for a diverse range of analytical applications, including the detection of O2· -production, [17][18][19] riboflavin and isatin based on the enhancement of ECL signals. 20,21 Recently, Dai et al proposed a novel analytical method for the determination of bisphenol A based on its strong inhibition phenomenon to the Luc 2+ ECL response.…”

A general E-E/C mechanism for the counter-peak in luminol electrochemiluminescence

“…ECL is conventionally initiated by applying various electropulse signals such as symmetric double-step potential [6,7], triangle pulse [8], and low-frequency [9] and high-frequency [10] square-wave potentials in order to obtain strong ECL intensity and high sensitivity. Alternatively, cyclic voltammetry [11][12][13][14][15][16][17][18][19][20][21][22][23][24] and linear sweep voltammetry [12] have also been utilized to generate ECL in different ECL systems, such as luminol [11][12][13][14][15], lucigenin [16,17], tris-(2,2 0 -bipyridyl) ruthenium (II) (TBR) [18][19][20], and semi-conductor nanoparticles [21][22][23][24] at various electrode materials by several groups. The curves of ECL intensity (I ECL ) versus potential (E) (I ECL -E curves) were obtained when such potential-scanning electrochemical techniques were utilized instead of potential-step methods.…”

Resistance to oxidative stress caused by ceftazidime and piperacillin in a biofilm of Pseudomonas

“…This DNA and other compounds come from the apoptosis of epithelial cells induced in response to P. aeruginosa strains able to activate cellular signalling pathways (3,4). P. aeruginosa employing chemiluminescence (CL) with lucigenin to detect reactive species of oxygen (ROS) (13), principally superoxide anion (O 2 − ) and hydrogen peroxide (H 2 O 2 ). These results motivated us to study the possible relationship between antibiotic action and increase of ROS in different bacterial species, in suspension or in a biofilm.…”