A Greener Chemiluminescence Demonstration

WARNING : The light-emitting molecular structures responsible for the chemiluminescence and fluorescence phenomena are not necessarily the same!

Chemiluminescent liposomes as a theranostic carrier for detection of tumor cells under oxidative stress

In the present study, we found that the absorbance at 395 nm of the chemiluminescent reaction system of eosin Y with hydrogen peroxide initially increased to a maximum, and then gradually decreased. From the finding that the absorption spectrum of a chromatographically-isolated blue-fluorescent product (ME) showed a peak at the same wavelength (395 nm), we could confirm that the increment of the absorbance at 395 nm (Δ395) was mainly due to the generation of ME; we then extended the investigation of the mechanism for the chemiluminescent reaction by a kinetic analysis of ME. The observed value of Δ395 could be approximately calculated by the expression of [ME], which was derived from a kinetic scheme proposed in the previous paper. The ratio of the generation rates of ME in different media, which was calculated from the observed values of Δ395, was in good agreement with that estimated from the curves of the chemiluminescence emission intensity versus the time measured in the media. These results gave additional evidence in support of the view that the blue-fluorescent species is the primary excited product in the reaction.

A novel chemiluminescence (CL) reaction, captopril-H2O2, for determination of Cu(II) at nanogram per milliliter level in batch-type system has been described. The method relies on the catalytic effect of Cu(II) on the oxidation of captopril with hydrogen peroxide in alkaline medium. The optimization step was performed using univariate methodology and the factors studied were: pH and concentrations of the utilized reagents. Under the optimum conditions, calibration plot was linear in the range of 0.1-2.0 ppm. Limit of detection was 30 ppb and relative standard deviation for five replicate determinations of 0.8 ppm Cu(II) was 1.89%. The proposed method was successfully applied to the determination of Cu(II) in human scalp hair and cereals, rice and wheat, flour with satisfactory selectivity and sensitivity. The results were validated by comparison with a standard method (FAAS). The possible mechanism of the new CL reaction has also been discussed.

Here, we report a hydrothermally treated green leaves (Moringa oleifera) extract exploited as an efficient and highly sensitive catalyst to catalyze the chemiluminescence (CL) reaction of luminol. In the absence of enhancer, this green and hydrothermally treated catalyst was found to significantly enhance the CL intensity ~3.5-fold compared with the traditionally used K3 Fe(CN)6 catalyst. The structure and surface morphology of the catalyst was elucidated using X-ray photoelectron spectroscopy, scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. The synergistic effect of the catalyst in the CL reaction was systematically investigated in the presence of hydrogen peroxide using ultraviolet-visible and CL spectroscopy. Studies showed that the sensitivity of the catalyst could be amplified by adjusting several parameters such as pH of the medium and concentrations of the base and luminol. The sensitivity of the novel-type catalyst was examined through the validation of hydrogen peroxide levels in commercial hair dye samples. Markedly, the catalyst displayed ultrasensitivity to hydrogen peroxide as the limit of detection of hydrogen peroxide using this catalyst was determined to be 0.02 μM under optimized conditions. In general, the proposed inexpensive, ecofriendly, and nontoxic catalyst could enable the determination of hydrogen peroxide for diverse analytical applications.

Catalytic behaviour of iron(II)-oxime complexes in the chemiluminescence reaction of luminol with hydrogen peroxide

An automated analysis system is described for the measurement of hydrogen peroxide based on a chemiluminescence reaction with phenyl 10-methylacridinium-9-carboxylate (PMAC). A reversed FIA experimental arrangement is used to establish the operating conditions for the measurement of submicromolar levels of hydrogen peroxide. The carrier stream consists of hydrogen peroxide standards prepared in a pH 9.0, boric acid buffer and the flow rate for this carrier/sample stream is 4 ml/min. Twenty microliters of a 10 mM PMAC solution, prepared in a pH 3 phosphate buffer, are injected into the carrier/sample stream. Hydrogen peroxide mixes with the PMAC reagent in an incubation coil that is constructed by wrapping 107 cm of polyethylene tubing around a 1 cm o.d. plastic rod. The chemiluminescence reaction is then initiated by adding base just before the sample passes in front of a photomultiplier tube (PMT) detector. The calculated limit of detection (S/N = 3) for hydrogen peroxide is 0.25 μM. In addition, the pH dependent hydrolysis of the PMAC reagent is characterized by an HPLC method which has been specifically developed for the separation and detection of the hydrolysis products of PMAC. Results indicate that a pH of 3.0 is required for long term stability of the PMAC reagent. Finally, this system has been successfully extended to the measurement of glutamate by coupling a bioreactor column of glutamate oxidase with the hydrogen peroxide detection scheme. A detection limit (S/N = 3) of 0.5 μM has been established for glutamate with a throughput of 200 samples per hour.

It has been shown that 1,1'-oxalyldiimidazole (ODI) is formed as an intermediate in the imidazole-catalyzed reaction of oxalate esters with hydrogen peroxide. Therefore, the kinetics of the chemiluminescence reaction of 1,1'-oxalyldiimidazole (ODI) with hydrogen peroxide in the presence of a fluorophore was investigated in order to further elucidate the mechanism of the peroxyoxalate chemiluminescence reaction. The effects of concentrations of ODI, hydrogen peroxide, imidazole (ImH), the general-base catalysts lutidine and collidine, and temperature on the chemiluminescence profile and relative quantum efficiency in the solvent acetonitrile were determined using the stopped-flow technique. Pseudo-first-order rate constant measurements were made for concentrations of either H2O2 or ODI in large excess. All of the reaction kinetics are consistent with a mechanism in which the reaction is initiated by a base-catalyzed substitution of hydrogen peroxide for imidazole in ODI to form an imidazoyl peracid (Im(CO)2OOH). In the presence of a large excess of H2O2, this intermediate rapidly decays with both a zero- and first-order dependence on the H2O2 concentration. It is proposed that the zero-order process reflects a cyclization of this intermediate to form a species capable of exciting a fluorophore via the "chemically initiated electron exchange mechanism" (CIEEL), while the first-order process results from the substitution of an additional molecule of hydrogen peroxide to the imidazoyl peracid to form dihydroperoxyoxalate, reducing the observed quantum yield. Under conditions of a large excess of ODI, the reaction is more than 1 order of magnitude more efficient at producing light, and the quantum yield increases linearly with increasing ODI concentration. Again, it is proposed that the slow initiating step of the reaction involves the substitution of H2O2 for imidazole to form the imidazoyl peracid. This intermediate may decay by either cyclization or by reaction with another ODI molecule to form a cyclic peroxide that is much more efficient at energy transfer with the fluorophore. The reaction kinetics clearly distinguishes two separate pathways for the chemiluminescent reaction.

A study of the chemiluminescence of some acidic triphenylmethane dyes

Here we report a new chemiluminescence reaction between basic aqueous H2O2 and acetonitrile. Its ultraweak chemiluminescence could be greatly enhanced by luminol, isoluminol-labeled streptavidin, and an Edman-type fluorescent reagent. Light emission was intense and long-lived, and this facilitated the initiation of the reaction and the measurement of the light emission. The present results permit us to propose a series of convenient, highly sensitive, and enzyme-free techniques for the detection and quantification of luminol, related conjugates, acetonitrile, and amino acids. Overall, this new chemiluminescence reaction will be quite promising for numerous applications in immunoassay, DNA hybridization, environmental monitoring. and postcolumn chromatographic detection.

A novel biosensor system for cyanide based on a chemiluminescence reaction

Ninhydrin was found to exhibit chemiluminescence (CL) when it was oxidized with hydrogen peroxide in neutral or weakly acidic solution. Copper(II) and CoII can catalyse the CL reaction, on the basis of which ppb levels of CuII and CoII can be determined. In the presence of CuII, some amino acids enhanced the CL reaction, whereas others inhibited the CL reaction in the presence of CoII. A flow-injection system with CL detection was developed for the determination of some amino acids. The mechanism of the CL reaction is discussed.

A novel plant tissue-based chemiluminescence (CL) biosensor for oxalate combined with flow injection analysis is proposed in this paper. The analytical reagents involved in the CL reaction, including luminol and cobalt(II), were both immobilized on an ion exchange resin column, while the biological material spinach tissue was packed in a mini-glass column. By the oxalate oxidase-catalyzed reaction in the plant tissue column, hydrogen peroxide was produced, which could react with luminol and cobalt(II) being released from the ion exchange column by hydrolysis to generate a CL signal. The CL emission intensity was linear with oxalate concentration in the range 0.6–100 µM and the detection limit was 0.2 µM. The biosensor was stable for 300 determinations and a complete analysis, including sampling and washing, could be performed in 2 min with a relative standard deviation of less than 5%.In recent years, traditional enzyme biosensors have been challenged by biosensors which use new biocatalytic materials, including animal and plant tissues1–3 and microorganisms.4–6 The catalytic function of these types of biosensors is due to the enzymes linked with metabolic pathways which exist either in the cytoplasmic membranes or directly inside the cells of these materials. Compared to biosensors with immobilized isolated and pure enzymes, such biosensors with immobilized tissues or whole cells show potential advantages of low cost, high stability, and a high level of enzyme activity. So far, most of them are bioselective membrane electrodes, in which the biocatalytic layer is usually retained physically at the detecting electrode surface with a support membrane and the analyte is sensed by diffusing through the test solution to the inner detector surface. However, these sensors often suffer from problems of long response time, low sensitivity and complex sensor assembly.Flow injection chemiluminescence (CL) analysis is becoming increasingly important in various fields for its high sensitivity, rapidity, simplicity and feasibility. Nowadays, CL flow sensing systems with immobilized reagents have received much attention and many applications have appeared in the literature.7–11 In these systems, analytes are detected by the CL reactions with the immobilized reagents directly or with the dissolved reagents which are released from the immobilized substrates by appropriate eluents. In this paper, a new type of biosensor, based on a plant tissue reactor, with flow injection CL detection for the determination of oxalate is proposed. It is prepared by using a spinach tissue column as the source of oxalate oxidase to catalyze the oxidation reaction of oxalate producing hydrogen peroxide, which is then detected by the CL reaction with luminol and cobalt(II) bleeding from an ion exchange column with immobilized reagents by hydrolysis.12

A review is given of chemiluminescent addition reactions between radicals and atoms, which might be suitable for high-pressure chemical lasers utilizing electronic transitions. Methods based on the experimental data on the spontaneous chemiluminescence or on the optical absorption in the reaction products are used to calculate the optical gain in a reacting mixture of gases, the frequency and temperature dependences of this gain, as well as the population inversion criterion. The following specific radiative reactions are considered: NO + O → NO2 + ħω, SO + O → SO2 + ħω, and 2Br → Br2 + ħω. The mechanisms of the emission of light are discussed.

The problem related to air discharge contaminated with volatile organic solvents (VOS) is the scope of numerous researches. Throughout the last decades, the development of different types of bioreactors to treat atmospheric emissions contaminated with VOS has been observed, such as: the bioscrubber, the percolating filter and the biofilter. These bioreactors are processes that use microorganisms in order to degrade the VOS into carbon dioxide, water, and biomass. This paper presents the results of a study on degradation by biofiltration of xylene contained in air, with a new filtering bed composed of cellulose. We have studied the conversion, the capacity of elimination of xylene with respect to the inlet load and the production of carbon dioxide. An elimination capacity of 75 g·m-3·h-1 for an inlet con centration to the biofilter of 1.7 g·m-3 of xylene has been obtained, which is a value that is superior to values mentioned in the literature. Measurements of temperature, pressure drop, and moisture content have been taken regularly so as to evaluate the influence of these parameters in the degradation process of xylene by microorganisms. Counts of bacteria and yeast/mould present in the filtering bed have been performed in order to follow the evolution of these micro organisms. At last, modeling based on the Ottengraf's model (1986) has been developed with the experimental data.Key words: treatment, air, biofiltration, xylenes, cellulose, volatile organic solvents.