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1.
A hybrid coordination complex, [(H5O2)(H2bpy)(bpy)4][NaMo8O26] · 2H2O (bpy = 4,4-bipyridine), was synthesized via hydrothermal reactions at 150 °C. The structure consists of two moieties; one is an infinite chain of β-[Mo8O26] clusters, each of which is inter-linked up by a sodium ion, and the other a two-dimensional network constructed from doubly protonated bpy ions and its neutral molecules, which are linked with water molecules by hydrogen bonds. The stacking of the networks provides one-dimensional tunnels suitable for Na-β-[Mo8O26] chains.  相似文献   

2.
Cardiolipin (CL) is a phospholipid predominantly found in the mitochondrial inner membrane and is associated structurally with individual complexes of the electron transport chain (ETC). Because the ETC is the major mitochondrial reactive oxygen species (ROS)-generating site, the proximity to the ETC and bisallylic methylenes of the PUFA chains of CL make it a likely target of ROS in the mitochondrial inner membrane. Oxidized cellular CL products, uniquely derived from ROS-induced autoxidation, could serve as biomarkers for the presence of the ROS and could help in the understanding of the mechanism of oxidative stress. Because major CL species have four unsaturated acyl chains, whereas other phospholipids usually have only one in the sn-2 position, characterization of oxidized CL is highly challenging. In the current study, we exposed CL, under aerobic conditions, to singlet oxygen (1O2), the radical initiator 2,2′-azobis(2-methylpropionamidine) dihydrochloride, or room air, and the oxidized CL species were characterized by HPLC-tandem mass spectrometry (MS/MS). Our reverse-phase ion-pair HPLC-MS/MS method can characterize the major and minor oxidized CL species by detecting distinctive fragment ions associated with specific oxidized species. The HPLC-MS/MS results show that monohydroperoxides and bis monohydroperoxides were generated under all three conditions. However, significant amounts of CL dihydroperoxides were produced only by 1O2-mediated oxidation. These products were barely detectable from radical oxidation either in a liposome bilayer or in thin film. These observations are only possible due to the chromatographic separation of the different oxidized species.  相似文献   

3.
The chemiluminescence (CL) of lucigenin (Luc2+) can be enhanced by different alcohols in alkaline solution. The effect of different fatty alcohols on the CL of lucigenin was related to the carbon chain length and the number of hydroxyl groups. Glycerol provides the greatest enhancement. UV/Vis absorption spectra and fluorescence spectra showed that N‐methylacridone (NMA) was produced in the CL reaction in the presence of different alcohols. The peak of the CL spectrum was located at 470 nm in all cases, indicating that the luminophore was always the excited‐state NMA. The quenching of lucigenin CL by superoxide dismutase (SOD) and the electron spin resonance (ESR) results with the spin trap of 5,5‐dimethyl‐1‐pyrroline N‐oxide (DMPO) demonstrated that superoxide anions (O2?–) were generated from dissolved oxygen in the CL reaction and that glycerol and dihydroxyacetone (DHA) can promote O2?? production by the reduction of dissolved oxygen in alkaline solution. It was assumed that the enhancement provided by different alcohols was related to the solvent effect and reducing capacity. Glycerol and DHA can also reduce Luc2+ into lucigenin cation radicals (Luc?+), which react with O2?? to produce CL, and glycerol can slowly transform into DHA, which is oxidized quickly in alkaline solution. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

4.
Cytochrome c (cyt c), a component of the respiratory chain, promotes apoptosis when released into the cytosol. Cyt c anchorage within mitochondria depends on cardiolipin (CL). Detachment and release have been related to CL loss and peroxidation. We report that NaN3-dependent complex IV inhibition, accompanied by impairment of respiration, resulted in cyt c release. Contrarily, inhibition of respiration upstream cyt c with complex I and III inhibitors was not accompanied by the release of the protein, despite CL decrease and monolyso-CL increase. No CL changes and H2O2 formation were observed by inhibiting complex IV. In cyt c–CL liposomes, breaching cyt c–CL hydrophilic interactions produced a higher release of the reduced, compared to the oxidized form, suggesting that the hydrophobic component of cyt c–CL binding is prevalent in the oxidized form. Free or liposome-reconstituted cyt c was able to form fatty acid–protein complexes (palmitate < linoleate < oleate) only in its reduced form. We hypothesize that reduced cyt c–fatty acid binding favors the dislocation of the protein from anchoring CL. A mechanism for cyt c release independent of CL peroxidation by H2O2 is feasible. It could weaken the hydrophobic component of cyt c–CL interactions and might function following complex IV inhibition or in oxygen lack, both conditions producing accumulation of reduced cyt c and free fatty acids.  相似文献   

5.
CoFe2O4 nanoparticles (NPs) could stimulate the weak chemiluminescence (CL) system of luminol and AgNO3, resulting in a strong CL emission. The UV–visible spectra, X‐ray photoelectron spectra and TEM images of the investigated system revealed that AgNO3 was reduced by luminol to Ag in the presence of CoFe2O4 NPs and the formed Ag covered the surface of CoFe2O4 NPs, resulting in CoFe2O4–Ag core–shell nanoparticles. Investigation of the CL reaction kinetics demonstrated that the reaction among luminol, AgNO3 and CoFe2O4 NPs was fast at the beginning and slowed down later. The CL spectra of the luminol ? AgNO3 ? CoFe2O4 NPs system indicated that the luminophor was still an electronically excited 3‐aminophthalate anion. A CL mechanism has been postulated. When the CoFe2O4 NPs were injected into the mixture of luminol and AgNO3, they catalyzed the reduction of AgNO3 by luminol to produce luminol radicals and Ag, which immediately covered the CoFe2O4 NPs to form CoFe2O4–Ag core–shell nanoparticles, and the luminol radicals reacted with the dissolved oxygen, leading to a strong CL emission. With the continuous deposition of Ag on the surface of CoFe2O4 NPs, the catalytic activity of the core–shell nanoparticles was inhibited and a decrease in CL intensity was observed and also a slow growth of shell on the nanoparticles. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

6.
A flow injection chemiluminescence (FI–CL) method was developed for the determination of cyanide (CN) based on the recovered CL signal by Cu2+ inhibiting a glutathione (GSH)‐capped CdTe quantum dot (QD) and hydrogen peroxide system. In an alkaline medium, strong CL signals were observed from the reaction of CdTe QDs and H2O2, and addition of Cu2+ could cause significant CL inhibition of the CdTe QDs–H2O2 system. In the presence of CN, Cu2+ can be removed from the surface of CdTe QDs via the formation of particularly stable [Cu(CN)n](n‐1)– species, and the CL signal of the CdTe QDs–H2O2 system was efficiently recovered. Thus, the CL signals of CdTe QDs–H2O2 system were turned off and turned on by the addition of Cu2+ and CN, respectively. Further, the results showed that among the tested ions, only CN could recover the CL signal, which suggested that the CdTe QDs–H2O2–Cu2+ CL system had highly selectivity for CN. Under optimum conditions, the CL intensity and the concentration of CN show a good linear relationship in the range 0.0–650.0 ng/mL (R2 = 0.9996). The limit of detection for CN was 6.0 ng/mL (3σ). This method has been applied to detect CN in river water and industrial wastewater with satisfactory results. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

7.
Luminol and lucigenin chemiluminescence (CL) responses produced by separated human blood polymorphonuclear leukocytes (pmn) and monocytes (mono) have been studied following stimulation with the surface-receptor agonist fMLP (a synthetic chemotactic peptide) and the protein kinase C activator phorbol myristate acetate (PMA). Pmn produced two- to threefold the luminol CL and superoxide anion (O2) levels of mono; lucigenin CL was similar for both cell-types. The myeloperoxidase (MPO) inhibitor salicylhydroxamic acid (SHA) abrogated luminol but not lucigenin CL in both cell types, but did not further inhibit the already grossly subnormal luminol CL responses seen with MPO-deficient cells which produced normal lucigenin CL. SHA also profoundly inhibited the luminol CL response in a cell-free MPO–H2O2 system. Mono lucigenin CL does not appear to specifically measure O2 production. These data show that luminol CL provides a useful measure of pmn and also mono MPO activity. However, analysis of the effects of various reactive oxygen species (ROS) scavengers, assessed on phagocyte and cell-free CL systems (both MPO–H2O2 and superoxide generating) suggest that the luminol CL signal is not entirely dependent on MPO activity.  相似文献   

8.
It was found that flavonoids could remarkably inhibit the chemiluminescence (CL) intensity of an off‐line gold nanoparticle (AuNP)‐catalyzed luminol–H2O2 CL system. By contrast, flavonoids enhanced the CL intensity of an on‐line AuNP‐catalyzed luminol–H2O2 CL system. In the off‐line system, the AuNPs were prepared beforehand, whereas in the on‐line system, AuNPs were produced by on‐line mixing of luminol prepared in a buffer solution of NaHCO3 ? Na2CO3 and HAuCl4 with no need for the preliminary preparation of AuNPs. The on‐line system had prominent advantages over the off‐line system, namely a lowering of the background noise and improvements in the stability of the CL system. The results show that differences in the signal suppression effect of flavonoids on the off‐line AuNP‐catalyzed CL system are influenced by the combined action of a free radical scavenging effect and occupy‐sites function; the latter was proved to be predominant using controlled experiments. Enhancement of the on‐line system was ascribed to the presence of flavonoids promoting the on‐line formation of AuNPs, which better catalyzed the luminol–H2O2 CL reaction, and the enhancement activity of the six flavonoids increased with the increase in reducibility. This work broadens the scope of practical applications of an AuNP‐catalyzed CL system.  相似文献   

9.
Chemiluminescence (CL) was observed when benzene vapour passed through the surface of Y2O3, TiO2, Y2O3–V2O5, TiO2–Y2O3, Y2O3–Cr2O3, Y2O3–Al2O3 and TiO2–Al2O3, with air as the carrier gas. The strongest CL intensity was found with Y2O3 as the catalyst. A novel benzene sensor based on this kind of CL was developed. Quantitative analysis was performed at the wavelength of 425 nm. Under optimal conditions, CL intensity was directly proportional to the concentration of benzene vapour. The linear range was 4–7018 mg/m3 (= 0.9981, = 11), with a detection limit of 1 mg/m3 (the signal:noise ratio was 3). This gas sensor can work continuously for >80 h and has been successfully applied to the real‐time determination of benzene vapour. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

10.
Visible oscillating chemiluminescence (CL) of luminol–H2O2–KSCN–CuSO4 was studied using the organic base (2‐hydroxyethyl)trimethylammonium hydroxide. The effect of concentrations of luminol, H2O2, KSCN, CuSO4 and the base were investigated in a batch reactor. This report shows how the concentration of components involved in the oscillating CL system influenced the oscillation period, light amplitude and total time of light emission. The oscillating CL with different bases was also investigated. Results indicated that using 2‐HETMAOH causes regular oscillating CL with nearly the same oscillating period. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

11.
In this paper, oscillating chemiluminescence (CL), 1,10‐phenanthroline H2O2–KSCN–CuSO4–NaOH system, was studied in a batch reactor. The system described is a novel, slowly damped oscillating CL system, generated by coupling the well‐known Epstein–Orban, H2O2–KSCN–CuSO4–NaOH chemical oscillator reaction with the CL reaction involving the oxidation of 1,10‐phenanthroline by hydrogen peroxide, catalyzed by copper(II) in alkaline medium. In this system, the CL reaction acts as a detector or indicator system of the far‐from‐equilibrium dynamic system. Narrow and slightly asymmetric light pulses of 1.2 s half‐width are emitted at 440 nm with an emitted light time of 200–1000 s, induction period of 3.5–357 s and oscillation period of 28–304 s depending on the reagent concentrations. In this report the effect of the concentration variation of components involved in the oscillating CL system on the induction period, the oscillation period and amplitude was investigated and the parameters were plotted with respect to reagent concentrations. Copper concentration showed a significant effect on the oscillation period. The possible mechanism for the oscillating CL reaction was also discussed. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

12.
The oxidation reaction of H2O2 with KIO4 can produce chemiluminescence (CL) in the presence of the surfactant Tween40 and the CL intensity of the CL system KIO4–H2O2–Tween40 can be strikingly enhanced after injection of tannic acid. On this basis, a flow injection method with CL detection was established for the determination of tannic acid. The method is simple, rapid and effective to determine tannic acid in the range of 7.0 × 10?9 to 1.0 × 10?5 mol/L with a determination limit of 2.3 × 10?9 mol/L. The relative standard deviation is 2.6% for the determination of 5.0 × 10?6 mol/L tannic acid (n = 11). The method has been applied to determine the content of tannic acid in industrial wastewater with satisfactory results. It is believed that the CL reaction formed singlet oxygen 1O2* and the emission was from an excited oxygen molecular pair O2(1Δg)O2(1?g) in the KIO4–H2O2–Tween40 reaction. Tween40 played an important role in enhancing stabilization of the excited oxygen molecular pair O2(1Δg)O2(1?g) and in increasing CL intensity. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

13.
A simple and sensitive DNA‐stablized gold nanoparticle (AuNP)‐based chemiluminescent (CL) probe for detecting mercury ion (Hg2+) in aqueous solution has been developed. The CL strategy relies upon the catalytic activity of unmodified AuNPs on the luminol–H2O2 CL reaction, and the interaction of unmodified AuNPs with DNA. The unmodified AuNPs can effectively differentiate unstructured and folded DNA. The DNA desorbs from AuNPs in the presence of Hg2+, leading to the increase in CL signal. By rationally varying the number of thymine in single‐strand oligonucleotides, the detection range could be tuned. Employing single‐strand oligonucleotides with 14 thymine in the detecting system, a sensitive linear range for Hg2+ ions from 5.0 × 10–10 to 1.0 × 10–7 mol/L and a detection limit of 2.1 × 10–10 mol/L are obtained. Changing the number of thymine to 10 and 6, it leads to a narrow detection range but a high sensitivity. Besides, DNA‐based CL nanoprobes exhibit a remarkable selectivity for Hg2+ ions over a variety of competing metal ions. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

14.
A simple one‐step thermal treatment to prepare strong fluorescent sulfur and nitrogen co‐doped graphene quantum dots (SN‐GQD) using citric acid and l ‐cysteine as precursors was developed. The ultra‐weak chemiluminescence (CL) from the reaction of hydrogen peroxide (H2O2) and periodate (IO4?) was significantly enhanced by SN‐GQD in acidic medium. The enhanced CL was induced by excited‐state SN‐GQD (SN‐GQD*), which was produced from the transfer energy of (O2)2* and 1O2 to SN‐GQD and recombination of oxidant‐injected holes and electrons in SN‐GQD. In the presence of tryptophan (Trp), the CL intensity of the SN‐GQD–H2O2–KIO4 system was greatly diminished. This finding was used to design a novel method for determination of Trp in the linear range 0.6–20.0 μM, with a limit of detection (LOD) of 58.0 nM. Furthermore, Hg2+ was detectable in the range 0.1–9.0 μM with a LOD of 64.0 nM, based on its marked enhancement of the SN‐GQD–H2O2–KIO4 CL system. The proposed method was successfully applied to detect Trp in milk and human plasma samples and Hg2+ in drinking water samples, with recoveries in the range 95.7–107.0%.  相似文献   

15.
Lu Han  Ying Li  Aiping Fan 《Luminescence》2018,33(4):751-758
Peroxidase is a commonly used catalyst in luminol–H2O2 chemiluminescence (CL) reactions. Natural peroxidase has a sophisticated separation process, short shelf life and unstable activity, therefore it is important to develop peroxidases that have both high catalytic activity and good stability as alternatives to the natural enzyme. Gold nanoclusters (Au NCs) are an alternative peroxidase with catalytic activity in the luminol–H2O2 CL reaction. In the present study, ethanediamine was modified on the surface of Au NCs forming cationic Au NCs. The zeta potential of the cationic Au NCs maintained its positive charge when the pH of the solution was between 4 and 9. The cationic Au NCs showed higher catalytic activity in the luminol–H2O2 CL reaction than did unmodified Au NCs. A mechanism study showed that the better performance of cationic Au NCs may be attributed to the generation of 1O2 on the surface of cationic Au NCs and a positive surface charge, for better affinity to luminol. Cationic Au NC, acting as a peroxidase mimic, has much better stability than horseradish peroxidase over a wide range of temperatures. We believe that cationic Au NCs may be useful as an artificial peroxidase for a wide range of potential applications in CL and bioanalysis.  相似文献   

16.
The oxidation reaction between cerium(IV) and Tween 85 in sulfuric acid medium produced weak chemiluminescence (CL). In this paper, it was found that citrate could strongly enhance the CL of cerium(IV)–Tween 85–polyphenol system. Based on studies of ultraviolet–visible spectra and CL spectra, the CL enhancement mechanism had been proposed. It was surmised that the light emission was from an excited oxygen molecular pair O2(1Δg)O2(1g). The maximum emission wavelength was about 478 nm. The effects of 17 amino acids and 29 organic compounds on cerium(IV)–Tween 85–citrate CL were investigated by a flow injection procedure. This study showed the present system had a wide application for the determination of these compounds. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

17.
Reactive oxygen species (ROS) are presently thought to play important role in an increasing number of the physiological and pathological processes in living organisms. Various chemiluminescent (CL) compounds have been studied in order to find suitable and specific probes for the detection of particular ROS species. The CL of luminol is known to be non‐specific and can be induced by various oxidants. Two Cypridina luciferin analogues, CLA and MCLA, have been used for the detection of ROS in vivo. CLAs are thought to emit light only when reacting with superoxide and singlet oxygen. It is possible to distinguish the particular ROS by using a specific quencher or scavenger, e.g. superoxide dismutase (SOD) or sodium azide (NaN3). The CL reactions of luminol (3‐aminophthalhydrazide), CLA [2‐methyl‐6‐phenyl‐3,7‐dihydroimidazo(1,2α) pyrazin‐3‐one] and MCLA [2‐methyl‐6‐(p‐methoxyphenyl)‐3,7‐dihydroimidazo(1,2α) pyrazin‐3‐one] were studied in three hydrogen peroxide decomposition systems (H2O2–HRP; H2O2–CuSO4; and H2O2–NaOCl). The measurements were carried out in phosphate buffer, pH 7.4, at 25 °C, using a luminometer (Fluoroskan Ascent FL and Sirius C). NaN3 was used as the specific quencher of singlet oxygen. The results demonstrate that the proclaimed specifity of the CL of Cypridina luciferin analogues towards singlet oxygen has to be discussed. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

18.
A novel phenomenon of dual chemiluminescence (CL) was observed for the KIO4–luminol–Mn2+ system in strong alkaline solutions using the stopped‐flow technique. Scavenging study of the reactive oxygen species (ROS) suggested that the two CL peaks originated from different CL pathways precipated by distinct ROS (O2? and ?OH for the first peak, mainly 1O2 for the second peak). Generation of these ROS at different time intervals from the reactions involving IO4?, O2, and Mn2+ and their subsequent reactions with luminol induced the intense CL emission. The relative intensity of the two CL peaks can be tuned over a wide range by varying the concentrations of Mn2?, luminol and KIO4. Because of the involvement of different ROS in each pathway, the two CL peaks could respond quite differently to various substances. Moreover, variation of the intensity ratio of the two CL peaks altered the relative proportions of the corresponding ROS, thereby changing their responses to a given substance. The dual CL emission acts like a pair of tunable probes and it is believed that this CL system has great potential in analytical applications. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

19.
Acetaminophen, also called paracetamol, is found in Tylenol, Excedrin and other products as over–the‐counter medicines. In this study, acetaminophen as a luminol signal enhancer was used in the chemiluminescence (CL) substrate solution of horseradish peroxidase (HRP) for the first time. The use of acetaminophen in the luminol–HRP–H2O2 system affected not only the intensity of the obtained signal, but also its kinetics. It was shown that acetaminophen was to be a potent enhancer of the luminol–HRP–H2O2 system. A putative enhancement mechanism for the luminol–H2O2–HRP–acetaminophen system is presented. The resonance of the nucleophilic amide group and the benzene ring of acetaminophen structure have a great effect on O‐H bond dissociation energy of the phenol group and therefore on phenoxyl radical stabilization. These radicals act as mediators between HRP and luminol in an electron transfer reaction that generates luminol radicals and subsequently light emission, in which the intensity of CL is enhanced in the presence of acetaminophen. In addition, a simple method was developed to detect acetaminophen by static injection CL based on the enhanced CL system of luminol–H2O2–HRP by acetaminophen. Experimental conditions, such as pH and concentrations of substrates, have been examined and optimized. The proposed method exhibited good performance, the linear range was from 0.30 to 7.5 mM, the relative standard deviation was 1.86% (n = 10), limit of detection was 0.16 mM and recovery was 99 ± 4%. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

20.
Poly‐dimethylsiloxane (PDMS) films with 2D periodic inverted moth‐eye nanopatterns on one surface are implemented as antireflection (AR) layers on a glass substrate for efficient light capture in encapsulated organic solar cells (OSCs). The inverted moth‐eye nanopatterned PDMS (IMN PDMS) films are fabricated by a soft imprint lithographic method using conical subwavelength grating patterns formed by laser interference lithography/dry etching. Their optical characteristics, together with theoretical analysis using rigorous coupled‐wave analysis simulation, and wetting behaviors are investigated. For a period of 380 nm, IMN PDMS films laminated on glass substrates exhibit a hydrophobic surface with a water contact angle (θCA) of ≈120° and solar weighted transmittance (SWT) of ≈94.2%, both significantly higher than those (θCA≈ 36° and SWT ≈ 90.3%) of bare glass substrates. By employing IMN PDMS films with a period of 380 nm on glass substrates for OSCs, an enhanced power conversion efficiency (PCE) of 6.19% is obtained mainly due to the increased short‐circuit current density (Jsc) of 19.74 mA cm‐2 compared to the OSCs with the bare glass substrates (PCE = 5.16% and Jsc = 17.25 mA cm‐2). For the OSCs, the device stability is also studied.  相似文献   

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