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PubMedDate not supplied

Long-lasting chemiluminescence of luminol on electrochemically pre-oxidized platinum electrodes in NaOH solution.

A long-lasting bright chemiluminescence (CL) of luminol was generated at polycrystalline platinum electrodes with open circuit. The CL can last for several hours with the presence of O(2) in the solution when the electrode was preoxidized at potentials more positive than 1.10 V vs. SCE. The effects of the varieties of solution conditions and surface states of the electrode on the CL intensity and the interfacial potential of the electrode were investigated. It was proposed that PtO was generated at the pre-oxidized potentials and played a role of catalyst of luminol oxidation for generating the CL. The redox couple of PtO/Pt(active) at the electrode surface was maintained in the presence of O(2) and luminol, and generated the interfacial potential more positive than 140 mV. Mathematical treatment of the reaction mechanism was conducted, which led to an approximated expression of a steady CL intensity (I(CL)) as a function of the pre-polarization potential (E( h)) and time (tau( h)) of the electrode. An empirical equation, (I(CL))(4/3) = 3480(-1 + 0.82E( h) + 0.037 ln tau( h)), was estimated from the experimental data.

Electrochemistry↗
PubMedDate not supplied

The effect of quenchers on the chemiluminescence of luminol and lucigenin.

The chemiluminescence of luminol and lucigenin is often used to detect the production of reactive oxygen derivatives by phagocytic cells. Also, several quenchers and enzyme inhibitors are used to determine which oxygen derivatives are responsible for the observed effects. In the present work we have assessed the reliability of dimethylthiourea and cysteamine (OH. quenchers), desferrioxamine (iron chelator) and diethyldithiocarbamate (superoxide dismutase inhibitor). They all react with CIO- and are also strong inhibitors of the luminescence of luminol catalysed by horseradish peroxidase (HRP); cysteamine and diethyldithiocarbamate also react with H2O2. NaN3 is an inhibitor of myeloperoxidase and a quencher of singlet O2, but we found that under certain conditions it can amplify the the luminescence of luminol triggered by CIO- or Fenton's reagent. A complex of copper and penicillamine that had been proposed as an O2-. quencher, quenches all luminescent reactions studied. On the other hand, we were able to confirm the relative specificity of other quenchers: taurine for CIO-, benzoate for OH. and mannitol for both OH. and 'crypto-OH.'.

Acridines↗
PubMedDate not supplied

The effect of buffers and chelators on the reaction of luminol with Fenton's reagent near neutral pH.

The chemiluminescence of the system luminol +Fe2+ +H2O2 was measured in aqueous buffer at pH 7.2. In veronal (5,5-diethybarbiturate) buffer, the luminescence is strongly quenched by ethanol and mannitol, but only weakly by t-butanol, benzoate and superoxide dismutase (SOD); complexing Fe2+ with 1,20-phenanthroline or 2,2'-dipyridyl causes a decrease of light production that can be partially obviated by the simultaneous addition of SOD. In phosphate buffer, the luminescence is higher than in veronal and it is efficiently quenched by all four OH. quenchers and by SOD. In Tris buffer, no light production is observed as long as the Fe2+ is not complexed. When Fe2+ is complexed by pyrophosphate or phytate, there is a strong chemiluminescence in all three buffers, which is quenched by all four OH. quenchers and by SOD. When Fe2+ is complexed by EDTA or DTPA, very little luminescence is observed. The luminol analogue phthalhydrazide, which was suggested by Merényi and Lind as a reliable OH. detector, can replace luminol only in phosphate buffer, and thus turns out to be very specific indeed for free OH..

Buffers↗
PubMedDate not supplied

Mechanisms of inhibition of chemiluminescence in the oxidation of luminol by sodium hypochlorite.

Two different mechanisms of inhibition of chemiluminescence in the oxidation of luminol by sodium hypochlorite were found. Most substances investigated in these experiments acted by scavenging NaOCl. This mechanism was independent of the concentration of hydrogen peroxide and the incubation time between luminol and inhibitors. The most potent inhibitors were substances containing SH groups. Compounds with amino groups as a target for HOCl/OCl- to yield chloramines were much less effective inhibitors. Another mechanism of inhibition was found for catalase. It depended on the presence of hydrogen peroxide in the incubation medium and the incubation time between luminol and catalase. The enzyme inhibited the luminescence by removing H2O2 at molar concentrations much smaller than those found for all other inhibitors. Our results confirm the present models of the mechanism of generation of luminescence in luminal oxidation.

Kinetics↗
PubMedDate not supplied

Characterization of peroxidases in luminol chemiluminescence coupled with copper-catalysed oxidation of cysteamine.

Hydrogen peroxide formed during the course of the copper(II)-catalysed oxidation of cysteamine with oxygen was continuously determined by a peroxidase (POD)-catalysed luminol chemiluminescence (CL) method. Horseradish peroxidase (HRP), lactoperoxidase (LPO) and Arthromyces ramosus peroxidase (ARP) were used as a CL catalyst. The respective PODs gave specific CL intensity-time profiles. HRP caused a CL delay, and ARP gave a time-response curve which followed the production rate of H2O2. LPO gave only a weak CL flash which decayed promptly. These differences of CL response curves could be explained in terms of the different reactivities of PODs for superoxide anion and the different formation rate of luminol radicals in the peroxidation of luminol catalysed by POD.

Copper↗
PubMedDate not supplied

Ticlopidine augments luminol-dependent chemiluminescence in human neutrophils.

Neutrophils contribute to the pathophysiology of various ischaemic states. Since many agents thought to be antiplatelet have also been shown to affect neutrophil function, it was of interest to examine the effect of ticlopidine (250 mg, p.o., b.i.d. for three doses), an antiplatelet agent, on fMLP (formyl-methionyl-leucyl-phenylalanine) stimulated neutrophil aggregation and luminol-dependent chemiluminescence in whole blood. Neutrophil aggregation did not significantly change from baseline values during ticlopidine administration. However, luminol-dependent chemiluminescence, an index of respiratory burst metabolism, was noted to be markedly increased during ticlopidine administration. Two hours following the final dose of ticlopidine, the chemiluminescent response (mean +/- SEM, n = 5) was significantly increased from 6.27 +/- 1.88 to 12.66 +/- 2.19 units (p < 0.05). A return to baseline (6.68 +/- 2.24 units) five days following the administration of ticlopidine was noted. It is concluded from this study that the acute oral administration of ticlopidine may affect neutrophil function as demonstrated by the significant increase in stimulated luminol-dependent chemiluminescence.

Adenosine Diphosphate↗
PubMedDate not supplied

Electrogenerated chemiluminescence of luminol for oxidase-based fibre-optic biosensors.

The luminol electrochemiluminescence has been exploited for the development of several fibre-optic biosensors allowing the detection of hydrogen peroxide and of substrates of H(2)O(2)-producing oxidases. Electro-optical flow injection analysis of glucose, lactate, cholesterol and choline are thus described. To perform the experiments, a glassy carbon electrode was polarized at a fixed potential. Luminol was then electrochemically oxidized and could react in the presence of hydrogen peroxide to produce light. Several parameters had to be optimized to obtain reliable optical biosensors. An optimum applied potential of +425 mV between the glassy carbon electrode and the platinum pseudo-reference electrode was determined, allowing the best signal: noise ratio to be obtained. It was also necessary to optimize the experimental conditions for the immobilization of the different oxidases involved (preactivated membranes, chemically activated collagen membranes, photopolymerized matrix). For each biosensor developed, the optimum reaction conditions have been studied: buffer composition, pH, temperature, flow rate and luminol concentration. Under optimal conditions, the detection limits (S/N = 3) were 30 pmol, 60 pmol, 0.6 nmol and 10 pmol for lactate, glucose, cholesterol and choline, respectively. The miniaturization of electrochemiluminescence-based biosensors has been realized using screen-printed electrodes instead of a glassy carbon macroelectrode, with choline oxidase as a model H(2)O(2)-generating oxidase.

Alcohol Oxidoreductases↗
PubMedDate not supplied

Increasing the specificity of the forensic luminol test for blood.

It is shown that the presumptive luminol chemiluminescence test for the presence of traces of blood can be made more determinative by measuring the peak emission wavelength of the luminol chemiluminescence. When sprayed onto a surface containing traces of human haemoglobin, a 1 g/L solution of aqueous luminol containing 7 g/L sodium perborate gives an emission peak at 455 +/- 2 nm, whereas the same mixture gives an emission peak at 430 +/- 3 nm when sprayed onto a surface containing traces of sodium hypochlorite (household bleach). This spectral difference can readily be determined using spectroscopic equipment that either scans the spectrum before significant luminescence decay occurs or corrects the spectrum for the effects of any decay. It was found that bovine haemoglobin and human haemoglobin showed no significant spectral differences.

Animals↗
PubMedDate not supplied

Increased carbon disulfide-stimulated chemiluminescence in the pyrogallol-luminol system.

We studied the effect of carbon disulphide (CS2) on the generation of superoxide anion (O2-*) and its chemiluminescence (CL) in the pyrogallol-luminol system. Testing was conducted with the pyrogallol-luminol system to observe the CL dynamic curve of CS2 and the inhibition by superoxide dismutase (SOD) on CL induced by CS2. Compared with the ethanol solvent control, CS2 enhanced the emission intensity of CL and delayed the peak time. There was a significant dose-concentration relationship between CS2 concentrations (10, 40, 80 mg/mL) and CL peak (r = 0.975 p = 0.012) and CS2 concentrations and peak time (r = 0.990, p = 0.005). The CL peak at 80 mg/mL CS2 was higher than that in a background without ethanol. The enhanced CL evoked by CS2 could be inhibited by SOD. The results suggest that CS2 can induce the pyrogallol-luminol system to generate an increased amount of O2-* and delay the CL peak time.

Carbon Disulfide↗
PubMedDate not supplied

A study of common interferences with the forensic luminol test for blood.

A wide range of domestic and industrial substances that might be mistaken for haemoglobin in the forensic luminol test for blood were examined. The substances studied were in the categories of vegetable or fruit pulps and juices; domestic and commercial oils; cleaning agents; an insecticide; and various glues, paints and varnishes. A significant number of substances in each category gave luminescence intensities that were comparable with the intensities of undiluted haemoglobin, when sprayed with the standard forensic solution containing aqueous alkaline luminol and sodium perborate. In these cases the substance could be easily mistaken for blood when the luminol test is used, but in the remaining cases the luminescence intensity was so weak that it is unlikely that a false-positive test would be obtained. In a few cases the brightly emitting substance could be distinguished from blood by a small but detectable shift of the peak emission wavelength. The results indicated that particular care should be taken to avoid interferences when a crime scene is contaminated with parsnip, turnip or horseradish, and when surfaces coated with enamel paint are involved. To a lesser extent, some care should be taken when surfaces covered with terracotta or ceramic tiles, polyurethane varnishes or jute and sisal matting are involved.

Animals↗
PubMedDate not supplied

A comparative study of bovine blood and milk neutrophil functions with luminol-dependent chemiluminescence.

In this study, a technique was developed for the chemiluminescence (CL) measurement of bovine milk polymorphonuclear leukocytes (PMN). In the first study, the effects of cell number and the concentration of phorbol-12-myristate-13-acetate (PMA), luminol, latex bead particles, dimethyl sulphoxide (DMSO) and gelatin on the luminol-dependent cellular CL (LDCL) response were assessed with healthy cows in different stages of lactation. In the second study, the LDCL and in vitro bactericidal activity of blood and milk PMN towards Staphylococcus aureus was investigated. In general, the CL activity of blood PMN was consistently higher than that of milk PMN. We found that (a) the optimal cell density in blood and milk cells for maximal LDCL response ranged from 1.5 x 10(6) to 5 x 10(6) cells/mL; (b) the optimal concentrations of PMA, latex beads and luminol for maximal LDCL response were 100-200 ng/ml, 500 particles/PMN and 0.1 mmol/L, respectively. Concentrations of DMSO of 0.5-1% (v/v) did not significantly affect the maximal CL response of PMN. Gelatin concentrations of 0.1 -0.5 mg/ml had no effect on the LDCL of PMN. In addition, the LDCL of PMN was significantly correlated with bactericidal activity towards S. aureus (r = 0.78, p < 0.001 for blood PMN and r = 0.66, p < 0.01 for milk PMN). Under the optimal experimental conditions for measurement of CL produced by bovine blood and milk PMN defined in this study, LDCL assay is an accurate and reproducible technique for the rapid quantification of PMN bactericidal activity in physiological and pathological conditions of high-yielding dairy cows.

Algorithms↗
PubMedDate not supplied

The forensic use of luminol chemiluminescence to detect traces of blood inside motor vehicles.

The luminol test for blood was carried out on a set of interior fittings and surfaces inside three different makes of modern motor car. The surfaces and fittings provided little interference with the test for blood, although there was some detectable chemiluminescence when the test was applied to blood-free material from a seatbelt, a boot-lining and a gear-knob. The case with which haemoglobin samples could be washed off interior car surfaces was also examined for seat fabrics, carpets, roof-linings and various other plastic interior surfaces. A standard wash with water alone was not very effective and removed only ca. 50% of the haemoglobin. A standard wash with soapy water or with a proprietary multipurpose car cleaner removed ca. 90% of the haemoglobin from the tested surface. The effect of high car interior temperatures on haemoglobin samples that were subsequently used in the luminol test was also examined. It was shown that the sensitivity of the luminol test was not decreased but was increased by the prior heating of a haemoglobin sample. This effect was attributed to the thermal conversion of haemoglobin to the more brighter catalyst for chemiluminescence, methaemoglobin. The enthalpy of this conversion in the solid state was found to be 14.1 kJ/mol.

Blood Chemical Analysis↗
PubMedDate not supplied

Attempted cleaning of bloodstains and its effect on the forensic luminol test.

The forensic luminol test has long been valued for its ability to detect trace amounts of blood that are invisible to the naked eye. This is the first quantitative study to determine the effect on the luminol test when an attempt is made to clean bloodstained tiles with a known interfering catalyst (bleach). Tiles covered with either wet or dry blood were tested, and either water or sodium hypochlorite solution (bleach) was used to clean the tiles. As expected, the chemiluminescence intensity produced when luminol was applied generally decreased with the number of times that a tile was cleaned with water, until the chemiluminescence was neither visible nor detectable. However, when the tiles were cleaned with bleach there was an initial drop in chemiluminescence intensity, followed by a rise to a consistently high value, visibly indistinguishable from that of blood. Examination of bleach drying time suggested that any interfering effect becomes negligible after 8 h.

Blood Stains↗
PubMedDate not supplied

A comparison of the presumptive luminol test for blood with four non-chemiluminescent forensic techniques.

Presumptive blood detection tests are used by forensic investigators to detect trace amounts of blood or to investigate suspicious stains. Through the years, a number of articles have been published on the popular techniques of the day. However, there is no single paper that critiques and compares the five most common presumptive blood detection tests currently in use: luminol, phenolphthalein (Kastle-Meyer), leucomalachite green, Hemastix and the forensic light source. The present authors aimed to compare the above techniques with regard to their sensitivity, ease of use and safety. The luminol test was determined to be the most sensitive of the techniques, while Hemastix is a suitable alternative when the luminol test is not appropriate.

Benzidines↗
PubMed1998

Analysis of prostaglandin G/H synthase-2 inhibition using peroxidase-induced luminol luminescence.

The inducible form of the heme-protein prostaglandin G/H synthase (PGHS-2 or COX-2) has been established as a pivotal enzyme in the cascade of events leading to inflammation, hyperalgesia, and pyresis and represents a major therapeutic target in inflammatory disease. Accordingly, we have exploited the heme-catalyzed hydroperoxidase activity of recombinant hCOX-2 to generate luminescence in the presence of luminol, or a cyclic naphthalene hydrazide, and the substrate arachidonic acid. Arachidonate-induced luminescence was shown to be an index of real-time catalytic activity and demonstrated the turnover inactivation of the enzyme. Luminol luminescence was proportional to hCOX-2 concentration and gave accurate Km determinations for arachidonate. Inhibition of hCOX-2 activity, measured by luminescence, by a variety of selective (for COX-2) and nonselective inhibitors showed rank orders of potency similar to those observed with other in vitro and whole cell methods using the recombinant protein. The sensitivity of the luminescence assay also allowed determination of inhibitor potency at substrate concentrations below Km, distinguishing competitive inhibitors such as ibuprofen from time-dependent inhibitors such as DuP-697. Finally the use of higher quantum-yielding luminol analogues allowed measurement of cyclooxygenase activity at extremely low substrate and protein concentrations, enabling a variety of novel assay formats.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1982

[Luminol chemiluminescence of phagocytosing polymorphonuclear leukocytes (author's transl)].

The oxidative metabolism, and thus the bactericidal activity, of neutrophil granulocytes can be evaluated by measurement of the luminol chemiluminescence during phagocytosis. The method described requires only a small number of separated cells (0.3 X 10(6)); continuous measurement in the physiologic temperature range is possible. The procedure is described and results of polymorphonuclear leukocytes from healthy adults and umbilical cord blood from healthy newborns are given. Quantitative variations in the single components (number of granulocytes, number of phagocytic particles, concentration of luminol) and the measuring volume are investigated. The significance of the chosen parameters "photon emission during defined time of measurement" and "time of maximum photon emission per unit time" used for evaluation is shown by comparison of the results from the influence of phorbol myristate acetate on the luminol chemiluminescence of phagocytosing granulocytes. The method described enables the evaluation of the capacity and the temporal course of stimulation of the oxidative metabolism of polymorphonuclear granulocytes in phagocytosis.

Adult↗
PubMed2001

Enhanced chemiluminescence for the oxidation of luminol with m-chloroperoxybenzoic acid catalyzed by microperoxidase 8.

The use of m-chloroperoxybenzoic acid (mCPBA) in stead of hydrogen peroxide causes an increase in chemiluminescence (CL) of luminol oxidation catalyzed by microperoxidase 8 (MP8) by an order of magnitude. The accelerated formation of an intermediate plays a major role in the CL enhancement, which also leads to a significant reduction in CL duration. The presence of guanidine hydrochloride, sodium carbonate, or sodium chloride further increases the CL emission drastically. The CL emission enhancement is strongly pH dependent. The enormous enhancement of the CL signal is due to an accelerated CL cycle and an improved CL efficiency in the presence of the enhancer. The CL signal covers several orders of magnitude over a wide range of concentrations of luminol and mCPBA. The intense CL of MP8-luminol-mCPBA in the presence of the enhancer will have great potential for extremely sensitive CL assays.

Animals↗
PubMed1988

A photodetection device for luminol-based immunodot and Western blotting assays.

A photodetection device permitting rapid and direct photographic recording of light emission from luminol-based immunodot and Western blotting assays is described in detail. This device permits contact exposure on Polaroid film of luminescent samples on nitrocellulose strips, and thus obviates the need for darkroom and film processing facilities. Immunodetection of mouse alpha-fetoprotein in brown fat homogenate and immunoglobulin E in nonimmune human sera employing luminol-based Western blotting and immunodot assays were used to demonstrate the versatility and operational simplicity of the detection device. The use of the detection device in combination with luminol-based immunoassays resulted in greater signal intensities and increased sensitivity over that attainable with the commonly used chromogenic substrate, 4-chloro-1-naphthol.

Adipose Tissue, Brown↗