Chemiluminescence Profiles Research Articles

In vitro evaluation of the behaviour of human polymorphonuclear neutrophils in direct contact with chitosan-based membranes

Several novel biodegradable materials have been proposed for wound healing applications in the past few years. Taking into consideration the biocompatibility of chitosan-based biomaterials, and that they promote adequate cell adhesion, this work aims at investigating the effect of chitosan-based membranes, over the activation of human polymorphonuclear neutrophils (PMNs). The recruitment and activation of polymorphonuclear neutrophils (PMNs) reflects a primary reaction to foreign bodies. Activation of neutrophils results in the production of reactive oxygen species (ROS) such as O 2 − and HO − and the release of hydrolytic enzymes which are determinant factors in the inflammatory process, playing an essential role in the healing mechanisms. PMNs isolated from human peripheral blood of healthy volunteers were cultured in the presence of chitosan or chitosan/soy newly developed membranes. The effect of the biomaterials on the activation of PMNs was assessed by the quantification of lysozyme and ROS. The results showed that PMNs, in the presence of the chitosan-based membranes secrete similar lysozyme amounts, as compared to controls (PMNs without materials) and also showed that the materials do not stimulate the production of either O 2 − or HO −. Moreover, PMNs incubated with the biomaterials when stimulated with phorbol 12-myristate 13-acetate (PMA) or formyl-methionyl-leucyl-phenylalanine (fMLP) showed a chemiluminescence profile with a slightly lower intensity, to that observed for positive controls (cells without materials and stimulated with PMA), which reflects the maintenance of their stimulation capacity. Our data suggests that the new biomaterials studied herein do not elicit activation of PMNs, as assessed by the low lysozyme activity and by the minor detection of ROS by chemiluminescence. These findings reinforce previous statements supporting the suitability of chitosan-based materials for wound healing applications.

Peak Formation Due to Chemiluminescence Reaction through the Collapse of Laminar Flow Liquid–Liquid Interface in a Microreactor

Abstract A peak signal due to a chemiluminescence (CL) reaction in a microreactor consisting of a microchannel without sample plug formation is presented. The CL reaction of luminol–hydrogen peroxide–Cu(II) was used in this study. A CL profile, including a peak signal, was observed by the collapse of the liquid–liquid interface based on laminar flow in the microchannel. We examined CL profiles for various flow rates of reagents and detection points in the microreactor. The data obtained were taken into consideration, together with the residence times and diffusion lengths. On the basis of on the measurements of peak height, Cu(II) was determined over the range of 20 nM–0.1 mM with a detection limit of 20 nM (S/N = 3).

The second time derivative analysis of chemiluminescence emission profiles and its application to the accurate determination of oxidative induction times

The technique of second time derivative (STD) analysis is developed and applied to the chemiluminescence (CL) profiles of two polypropylene (PP) formulations and a 5% w/w blend of polybutadiene (PBD) in PP to assess this novel method of analysis as a means of reliably determining the oxidative induction time (OIT) of polymers. It is proposed that the STD technique, when used in conjunction with the integrated CL profile, can enable evaluations of the OIT to be made that are less subjective than those made using the conventional extrapolation method. This is particularly so in systems that exhibit a gradual onset towards autoacceleration and/or convoluted CL profiles. Chemiluminescence profiles of the PBD–PP blend that were obtained at different temperatures were subjected to STD analysis, and Arrhenius plots of the data were made. The results are consistent with the notion that the PBD and PP phases oxidize almost independently. The activation energies for the oxidation of the PBD and PP phases were calculated to be 200 ± 31 kJ mol−1 and 146 ± 9 kJ mol−1, respectively. The higher activation energy for the PBD phase is partly attributed to the greater partitioning of thermal stabilizer in this phase. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1986–1993, 2001

Kinetics of Two Pathways in Peroxyoxalate Chemiluminescence

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.

Modulation of the chemiluminescent signal from N10-(3-sulfopropyl)- N-sulfonylacridinium-9-carboxamides

Acridinium salts 3a-h were synthesized from the corresponding sulfonamides 1a-h and their chemiluminescence profiles were compared. The quantity of light emitted over the time studied did not correlate well with the p K a of sulfonamide leaving group. Rather, steric factors contributed the most to modulating the light output from these compounds. The mesitylsulfonyl substituent of acridinium salt 3d reduced the chemiluminescence signal by 20-fold relative to the reference acridinium salt 3a.

The effect of pH on chemiluminescence of different probes exposed to superoxide and singlet oxygen generators

The compromised optima for high intensity chemiluminescence (CL), using superoxide generators, were all above pH 9.0 for the CL probes luminol and lucigenin. With luminol the optima were at pH 9.0 and 9.4 for the generators KO2 and hypoxanthine/xanthine oxidase (HX/XO), respectively. Lucigenin, with the same generators, produced optima at pH 9.5 and 10.0, respectively. The probe methyl-Cypridina-luciferin analogue (MCLA) produced optima closer to neutral pH, which is preferred for physiological assessments. MCLA had optima at pH 6.0, 8.7 and 9.5 with KO2 and with HX/XO optima at pH 4.8, 6.0, 7.0 and 8.7. When CL was assessed at physiological pH, MCLA observed superoxide radicals with a sensitivity of 100- and 330-fold more than luminol or luicigenin respectively. For singlet oxygen, the sensitivity of MCLA at this pH was 45- and 5465-fold more than for the said probes respectively. H2O2 did not elicit CL between pH 4 and 9.5 with any of the probes and did not influence the production of superoxide or singlet oxygen when co-assessed. Therefore CL could only be obtained when enzymes were used as converters. The optima for the enzyme-conversion system horseradish peroxidase (HRP)/H2O2, and luminol, were at pH 8.0 and 9.2. Lucigenin and HRP/H2O2 also had a biphasic CL profile with optima at pH 7.4 and 9.6. MCLA and HRP/H2O2 had five optima, with the major ones at pH 6.1 and beyond 10. The optima for the myeloperoxidase/H2O system were at 8.6 and beyond 10.0 when luminol and 0.15 mol/L NaBr were used.

Chemiluminescence measurement of gel times for amine-cured epoxy resins

The cross-linking reactions of 4,4'-diaminodiphenyl sulphone (DDS) with stoichiometric quantities of glycidyl ether- or tetraglycidyl amine-based epoxy resins were monitored using chemiluminescence (CL) and rheometry. It was found that, when a sample was cured isothermally in air, the CL profile increased to a maximum, then decreased again. The maximum was found to correspond well with the gel time (tgel), as measured by rheometry. This observation is discussed in relation to the chemical reactions occurring within the material and the physical state of the matrix. The effect of impurities in DDS on the gel time of these epoxy resins is reported.

Chemiluminescence in organized molecular assemblies: lucigenin derivatives containing long alkyl chains in micellar media

The chemiluminescent reaction of five N,N′-dilakyl-9,9′-biacridinium nitrates, C 1, C 4, C 6, C 10 and C 12, with hydrogen peroxide in alkaline aqueous and micellar solutions is reported. The chemiluminescence and chemiexcitation yields in these media are reported together with the chemical yields and the fluorescence quantum yields of the long chain N-alkylacridones, the primary emitters, in cationic, anionic and non-ionic micellar media. Based on the chemiluminescence profiles the reaction rate constants and chemiluminescence intensities are reported.

Kinetic investigation of the collisional quenching of Ca(43Pj) by C4H10at elevated temperatures (750–923 K). Time-resolved atomic emission and electronic energy transfer between Ca(43PJ) and CaH(X2Σ+) observed by Molecular Chemiluminescence

A detailed investigation is presented of the collisional removal of electronically excited calcium atoms, Ca[4s4p(3PJ)], 1.888 eV above its 4s2(1S0) ground state, with n-butane at elevated temperatures in a slow-flow system, kinetically equivalent to a static system. Ca(4 3PJ) was generated by pulsed dye-laser excitation of calcium vapour at λ= 657.3 nm [Ca(4 3P1)â†� Ca(4 1S0)] and monitored by time-resolved atomic fluorescence at the resonance wavelength over timescales during which Boltzmann equilibration had taken place with the 3PJ spin–orbit manifold. Absolute second-order rate constants for the collisional removal of Ca(4 3PJ) by butane were measured over the temperature range 750–923 K, yielding the following Arrhenius form: kR=(3.5+3.6–1.8)× 10–9 exp(– 58.7 ± 5.0 kJ mol–1/RT) cm3 molecule–1 s–1, The results are compared with analogous data derived from our previous investigations on the collisional removal of Mg(3 3PJ) by various hydrocarbons. Molecular chemiluminescence for the system CaH(A 2Π–X 2Σ+) was also monitored in the time domain following excitation of Ca(4 3PJ) and shown to arise from electronic energy transfer from Ca(4 3PJ) to ground-state CaH(X 2Σ+) both from its bi-exponential time dependence and the observation of CaH(X 2Σ+), generated in the reaction, by laser-induced fluorescence (LIF). CaH(X 2Σ+) was also detected by LIF from the reaction of Ca(4 1S0) in the flow, and the source of this is discussed. These CaH(A–X) chemiluminescence profiles which provide a spectroscopic marker for Ca(4 3PJ) in this type of system, coupled with the LIF observations on CaH(X) and constituting, to the best of our knowledge, the first observation of its type, are compared with analogous observations reported previously where molecular chemiluminescence from CaO is employed as a spectroscopic marker for Ca(4 3PJ) with oxidising reactants.

Depression of Phagocytic Activity of The Immune System Following Traditional Cautery in Experimental Animals

Traditional cautery, which is practiced widely in Saudi Arabia and some other countries, has not been exposed to detailed scientific investigation. In an attempt to elucidate some of its physiological aspects, we assessed the effect of cautery on a normal animal's nonspecific immune system. Male Wistar rats and guinea pigs were cauterized to simulate traditional cautery in size and percentage of cauterized area. Using radioactive sulfur colloid uptake and clearance, the effect of cautery on the mononuclear phagocyte system was evaluated in rats. The respiratory burst in peripheral polymorphonuclear leukocytes (PMNs) after cautery was measured in the guinea pigs using the chemiluminescence technique. The results showed marked reduction in the intravascular clearance of the colloid with prolonged clearance time following cautery. In addition, the liver uptake of the colloid was reduced in cauterized animals compared with control animals and the white cell count was also significantly reduced. The study showed marked inhibition of phagocytic function in guinea pigs in both whole blood and isolated PMNs. These results indicate that traditional cautery reduces the physiological function of the phagocyctic system in normal experimental animals. The influence of traditional cautery on infected animals deserved further investigation.

Investigation of Time‐Resolved Molecular Chemiluminescence from SrO(A'1 Π, A1Σ+ ‐ X1Σ+) and Atomic Emission from Sr(53P1 ‐ 51S0) Following Pulsed Dye‐Laser Generation of Sr(53PJ) in the Presence of CO2

AbstractWe present a kinetic study of chemiluminescence from SrO(A1Σ+ ‐ X1Σ+) and SrO(A'1 Π ‐ X1Σ+) following pulsed dye‐laser generation of Sr(5s5p(3PJ)), 1.807 eV above the 5s2(1S0) ground state, in the presence of CO2. This required complementary investigation of the time‐dependence of both the atomic emission profiles at the resonance wavelength of λ = 689.3 nm (Sr(5s5p(3P1)) Σ Sr(5s2(1S0)) + hv) and at wavelengths of various vibronic transitions within the A—X and A'— X band systems of SrO, together with the determination of the quantitative relationship between these using the appropriate time‐dependent equations for atomic and molecular emission. Decay profiles for Sr(53PJ) in the presence of CO2 across the temperature range T = 675—1100 K showed clear exponential decay behaviour, yielding the absolute second order rate constant for total collisional removal of the excited atoms of k1 = (4.7 ± 2.8) Σ 10−10 exp(‐ 33.3 ± 9.9 kJ mol−1 /RT) cm3 molecule −1 s−1. At elevated temperatures, the Arrhenius plot for the removal of Sr(53PJ) displayed upward curvature which is shown to be sensibly consistent with the removal of this atomic state by product SrO(X1Σ+). Chemiluminescence from transitions involving Δv sequences within SrO(A1Σ+ ‐ X1Σ+) and within the v = 0 progression of SrO(A'1Π ‐ X1Σ+) was monitored and analysed across the temperature range 900–1100 K. These molecular chemiluminescence profiles exhibited clear bi‐exponential behaviour which, when compared with the single exponential profiles for Sr(53PJ), were quantitatively shown to be consistent with the E—(E, V) transfer processes: Sr(53PJ) + SrO(X1Σ+) → SrO(A1Σ+, A'1Π, v' = n) + Sr(51S0). Vibrational excitation by this mechanism was observed up to the maximum energetically allowed by the relevant E ‐ (E, V) process. A ‐ X and A'‐ X chemiluminescence was shown to provide kinetic spectroscopic markers in the time‐domain for Sr(53PJ). Estimated vibrational temperatures within SrO(A'1II) indicated some measure of vibrational excitation accompanying energy transfer. The temperature variation of the SrO(A ‐ X) and SrO(A'‐X) emission intensity was demonstrated to be consistent with thermodynamic data for atomic strontium.

The Effect of Protein II and Pili on the Interaction of Neisseria gonorrhoeae with Human Polymorphonuclear Leucocytes

Colonial variants of Neisseria gonorrhoeae strain P9 expressing different pili and/or outer membrane protein II (P.II) were investigated with respect to their interaction with human polymorphonuclear leucocytes (PMN). Two assay systems were used. A phagocytic killing assay measured the intracellular survival of gonococci, and PMN chemiluminescence (CL) was used to determine the initial surface interactions. All variants expressing P.II were killed effectively by PMN and also greatly stimulated PMN CL. The P.II- variants, on the other hand, were resistant to phagocytic killing and stimulated a much lower CL response. The presence of different P.II species was associated with different CL profiles and therefore different modes of interaction with the PMN membrane. A P.II-specific monoclonal IgG was opsonic and greatly increased PMN CL in contrast to F(ab')2 prepared from the same antibody, which inhibited it, thus confirming the role of P.II in the PMN interaction. Phagocytic killing assays revealed that with the loss of P.II, gonococcal variants acquired resistance to killing. Comparison of piliated and non-piliated pairs of variants with the same P.II profile showed that PMN-gonococcal interactions are dominated by the nature of the P.II species present whereas pili have little effect.

Determination of the absolute rate constant for the reaction O + NaO → Na + O2by time-resolved atomic chemiluminescence at λ= 589 nm [Na(32PJ)→ Na(32S1/2)+hν

We present the first laboratory measurement of the absolute second-order rate constant for the overall removal of O(2 3PJ) by NaO: [graphic omitted] k2=k2a+k2b. NaO was generated at known concentrations in the presence of an excess of He in a slow-flow system by titrating N2O with Na derived from a heat-pipe oven via the reaction Na + N2O → NaO + N2. Atomic chemiluminescence at λ= 589 nm [Na(3 2PJ)→ Na(3 2S1/2)+hν] subsequent to pulsed irradiation was then monitored in the time domain following reaction (2b). Analysis of the chemiluminescence profiles yielded k2(T= 573 K)=(3.7 ± 0.9)× 10–10 cm3 molecule–1 s–1. The importance of this reaction in interpreting the mesopheric chemistry of sodium is considered in detail. An estimate of the branching ratio α=k2b/(k2a+k2b) from the present measurements of ca. 1 % indicates a value considerably lower than that based on statistical considerations alone and used previously in computer models of the mesosphere.