Chemiluminescent light emission

In electrogenerated chemiluminescence, light emission occurs not on the electrode surface but in the solution. Oxygen has to be excluded 5>. In the usual form a one-electrode technique is applied the potential of the electrode is changed periodically. At cathodic potential the radical anion is produced, at anodic potential the radical cation. These two radical ions react in the diffusion layer near the electrode surface the electron transfer from the radical anion to the radical cation causes the light emission 5>2°). 

All evaluations of this C-peptide assay performance were performed by LUMIPULSE FORTE. The method used on LUMIPULSE FORTE was as follows 20 pL of serum or standard was mixed with 250 pL of antibody-coated ferrite particle suspension and the mixture was incubated for 37 °C, 10 min. After B/F separation, 250 pL of Enzyme-labeled antibody was added to the ferrite particle suspension and the mixture was incubated for 37 °C, 10 min. After the second B/F separation, 200 pL of AMPPD solution was added. During the washing steps, the ferrite particles were magnetically separated from the bulk solution on the wall of the cartridge. After the enzyme reaction had proceeded for 5 min, the chemiluminescent light emission was measured for 2 s. 

BIOLUMINESCENCE AND CHEMILUMINESCENCE Light Emission Biology and Scientific Applications... 

Chemiluminescence—Light emission from chemical action, not... 

Reaction takes place ia aqueous solution with hydrogen peroxide and catalysts such as Cu(II), Cr(III), Co(II), ferricyanide, hernia, or peroxidase. Chemiluminescent reaction also takes place with oxygen and a strong base ia a dipolar aprotic solvent such as dimethyl sulfoxide. Under both conditions Qcis about 1% (light emission, 375—500 am) (105,107). 

Chemiluminescent labels, in which the luminescence is generated by a chemical oxidation step, and bioluminescent labels, where the energy for light emission is produced by an enzyme-substrate reaction, are additional labeling types (39,42). Luminol [521 -31 -3] CgHyN202, and acridine [260-94-6] C H N, derivatives are often used as chemiluminescent labels. 

Side reaction. The luminescence reaction of Cypridina luciferin catalyzed by luciferase involves a side reaction (Fig. 3.1.8). In the luminescence reaction, 85-90% of luciferin is converted into oxyluciferin and CO2 accompanied by light emission, whereas 10-15% of luciferin is converted directly into etioluciferin plus a keto-acid without light emission (Shimomura and Johnson, 1971). In the chemiluminescence reactions of Cypridina luciferin in organic solvents (such as diglyme, acetone, pyridine and DMSO), the proportion of the dark side reaction... 

Fig. 5.4 Chemical mechanism of light emission in the bio- and chemiluminescence reactions of coelenterazine. The bottom row shows some of the fluorescence emitters of coelenteramide. The fluorescence characteristics of the dianion are unknown.

Spontaneous light emission from fresh material. For mycelium, the two data shown are scraped mycelium / mycelium on agar before scraping. cChemiluminescence activity of the extract in the presence of Fe + and H2O2. dThe extract was activated with methylamine, and then chemiluminescence activity was measured. A minus sign (—) indicates an unsuccessful quantitation due to various causes. 

FIGURE 15.28 Chemiluminescence, the emission of light as the result of a chemical reaction, occurs when hydrogen peroxide is added to a solution of the organic compound perylene. Although hydrogen peroxide itself can fluoresce, in this case the light is emitted by the perylene. 

To our surprise and satisfaction, the general approach worked the CBI derivatives did chemiluminescence, and the sensitivity enhancement was 30- to 50-fold over fluorescence With this success, we embarked on a more thorough study of chemiluminescence with the goal of optimizing the method. Identifiable parameters that affected the efficiency of light emission from a chemically generated fluorescent molecule included ... 

Alkaline phosphatase-labeled probes are synthesized so that 18 bases are complementary to sequences on the arms of the bDNA. Three hybridization sites are located on each branch for a total binding capacity of 45 labeled probes per bDNA molecule. The alkaline phosphatase catalyzes the dephosphorylation of chemiluminescent substrate, dioxetane (Lumi-Phos Plus, Lumigen, Detroit, MI). The intensity of the light emission is measured with a plate luminometer as relative luminescent units. 

Light emission from the chemiluminescent substrate is directly proportional to the amount of the target nucleic acid in the sample, and the results are recorded as relative luminescence units (RLUs). All samples, standards, and controls are run in duplicate, and the mean RLU is used in data analysis. The percent coefficient of variation (%CV) for duplicate RLU for controls and samples must be within the recommended limit for that assay for the results to be valid. For example, negative samples must have a CV of <30% and positive samples <20% in the HCV assay. 

In the Hybrid-Capture assay (Digene), a full-length RNA probe is hybridized to denatured HBV DNA in solution and the hybrids are captured on the surface of a tube coated with anti DNA RNA hybrid antibody. The bound hybrids are reacted with antihybrid antibody labeled with alkaline phosphatase. A chemiluminescent substrate is converted to a luminescent compound by the bound alkaline phosphatase. Light emission is measured in a luminometer and the concentration of HBV DNA, in pg/ml, is determined from a standard curve. The concentrations of the standards are determined spectrometrically (A260nm/A280nm). 

The authors also demonstrated a low-technology method for recording the chemiluminescent signal of the bDNA assay. The light emission was recorded on black-and-white film Polaroid film using a handheld camera. The bDNA assay could be applicable to field situations because of the stability of the reagents and the ability to record the data without the use of sophisticated equipment. 

Mechanisms Leading to the Light Emission from Thermally Oxidized Polymers (Chemiluminescence), Similarities and Differences within Respective Groups of Polymers 463... 

MECHANISMS LEADING TO THE LIGHT EMISSION FROM THERMALLY OXIDIZED POLYMERS (CHEMILUMINESCENCE), SIMILARITIES AND DIFFERENCES WITHIN RESPECTIVE GROUPS OF POLYMERS... 

Chemiluminescence is light emission from the relaxation of electrons populating excited states in an elementary step of a chemical reaction. Since, the process of population of excited states is related kinetically to the kinetics of the given chemical reaction, the emission of chemiluminescence over time should thus be related to the rate of the chemical reaction. 

Figure 3 shows how the elementary structure of the polymer affects the observed patterns of chemiluminescence response in oxygen at 120°C. As expected, the oxidizability decreases in the order polyisoprene < polybutadiene < polypropylene < polyethylene. However, it is difficult to understand why the maximum light emission is almost 2x lower for polybutadiene than for PP. The oxidation of polybutadiene occurs via secondary peroxyl radicals, while in... 

Recently, we have shown that non-isothermal chemiluminescence measurements for oxidized cellulose provide the same rate constants of cellulose degradation as may be measured from experiments on the decay of polymerization degree determined by viscometry. This may be also taken as indirect evidence that the light emission is somehow linked with the scission of polymer chains [29]. 

The quality of the polymer, its photo-oxidation and thermo-oxidation history expressed in concentration of hydroperoxides, carbonyl groups or of other oxidized structures and terminal groups. The rate of an oxidative attack may then be related to the average molar mass and to its distribution, and to the ratio of amorphous/crystalline structures. Polymers cannot be simply ordered according to the intensity of light emission at a given temperature. The chemiluminescence-time patterns are related with the rate of sample oxidation, but they may differ from one to the next polymer. 

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