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High-efficiency chemiluminescence (CL) resonance energy transfer (CRET) can be obtained by shortening the donor-acceptor distance and/or improving the luminescence efficiency of CRET acceptors. However, careful design and stringent experimental conditions are usually required for the ordered assembly of CRET acceptors on support materials to avoid aggregation-caused quenching problems. In this work, an aggregation-induced emission (AIE)-active fluorophore was disorderly adsorbed on the surface of layered double hydroxides (LDHs), which could exhibit high-efficiency luminescence. On the other hand, the positively charged LDHs can further adsorb peroxynitrite (ONOO-) on the surface of LDHs. Therefore, the LDH-supported AIE fluorophore could dramatically amplify weak CL signals from ONOO- donors as a result of ultra-high CRET efficiency by coupling the shorter donor-acceptor distance with efficient CRET acceptors. The proposed CL system has been successfully applied for the detection of NaNO2 in the concentration range from 1.0 to 100 μM with a detection limit as low as 0.5 μM. Satisfactory recoveries (98-106%) and good accuracy were achieved for sausage samples. Our success will open new avenues for the convenient design of high-efficiency CRET systems.

Since its birth in 1967, the utilization of chemiluminescence resonance energy transfer (CRET) has made substantial progress in a variety of fields for its unique features. However, the quantitative relationship between CRET efficiency and donor-acceptor distance has not yet been determined owing to the difficulty in designing the variable lengths between chemiluminescent donors and acceptors. Herein, we synthesized three kinds of tetraphenylethene (TPE)-anchored cationic surfactants with aggregation-induced emission (AIE) characteristics. For the first time, it is quantitatively demonstrated that the CRET efficiency is inversely proportional to the sixth power of distance between luminol donors and TPE acceptors. The details disclosed in this contribute have provided the solid evidence that CRET follows Förster resonance theory. Our strategy would build a promising platform to control donor-acceptor distance, allowing to the interdisciplinary applications of CRET.

The formation of hydroxylated intermediates is the first step in the persulfate-based advanced oxidation processes (AOPs) and depends directly on the oxidation degree of recalcitrant pollutants. Th...

Luminol tablet-Tris-Co(ii) complex-PVP-H2O2 systems exhibit 13 hours of intensive and stable chemiluminescence (CL) due to the continuous generation of ˙OH and sustained-release. Multicolored chemical lights were prepared through CL resonance energy transfer. This work presents a new method for the fabrication of bright chemical lights in aqueous solution for emergencies.

Carminic acid (CA) extracted from cochineal is widely used in food additives as a natural colorant, and its potential risk to human health makes its detection important. In this work, a layered doubled hydroxide (LDH)–luminol–H2O2 system-based chemiluminescence (CL) platform has been successfully applied for CA sensing. The principle detection consists of two steps: first, LDH adsorbs CA onto the surface via electrostatic attraction; second, CA quenches the CL of the LDH–luminol–H2O2 system via the synergistic effect of CL resonance energy transfer, reduction of reactive oxygen species, and occupation of positively charged centers of brucite-like layers. With this CL approach, 0.5 μM CA is detectable using a CL spectrometer, and the limit of detection is 0.03 μM. This CL system exhibited a linear response to CA in the concentration range from 0.5 to 10 μM. In addition, the practical application of the designed CL sensing system is evaluated with dried pork slice samples.

HClO/ClO- is the most effective antibacterial active oxygen in neutrophils. However, its excessive existence often leads to the destruction of human physiological mechanisms. In recent years, the developed luminescent probes for the detection of HClO/ClO- are not only conducive to improve the sensitivity and selectivity of HClO/ClO- detection, but also play a crucial role in understanding the biological functions of HClO/ClO-. In addition, luminescent probe-based biological imaging for HClO/ClO- at sub-cellular resolution has become a powerful tool for biopathology and medical diagnostic research. This article reviews a variety of luminescent probes for the detection of HClO/ClO-in vitro and in vivo with different design principles and mechanisms, including fluorescence, phosphorescence, and chemiluminescence. The photophysical/chemical properties and biological applications of these luminescent probes were outlined. Finally, we summarized the merits and demerits of the developed luminescent probes and discussed their challenges and future development trends. It is hoped that this review can provide some inspiration for the development of luminescent probe-based strategies and to promote the further research of biomedical luminescent probes for HClO/ClO-.

In this report, a simple approach for generating chemiluminescence (CL) of hyperbranched polyethyleneimine protected silver nanoclusters (hPEI-AgNCs) in solution by hydroxyl radicals (˙OH) is proposed. Emission of this CL system originates from excited AgNCs rather than from reaction intermediates, which is different from other metal nanoclusters involving CL reactions. Notably, in the presence of tea polyphenols (TPPs), the ˙OH induced CL signal is restrained, which is due to the TPPs-induced reduction of ˙OH. Therefore, a facile CL approach for TPPs sensing based on the inhibition effect of TPPs towards the ˙OH has been developed. This simple CL detection method exhibits a linear response toward TPPs in the concentration range from 2.52 to 76.2 μM with a limit of detection of 2.52 μM. In addition, the proposed method displays high selectivity toward TPPs over other small molecules or metal ions, including L-theanine, L-alainine, L-asparagine, paraxanthine, glycine, glucose, Na+, K+, Mg2+, Zn2+ and Fe3+. Compared with reported colorimetric or fluorimetric approaches, this new system shows comparable or better selectivity. The proposed method can be readily used for TPPs content evaluation from tea sample infusions.

In this report, a simple chemiluminescence (CL) approach for detecting an anionic dye, alizarin red S (ARS), based on layered double hydroxides (LDHs)-improved CL from hydrogen peroxide (H2O2) and luminol system is proposed. The LDHs-improved H2O2–luminol CL is due to the adsorption of luminol dianion and peroxide anion onto the positively charged brucite-like layers and the facilitated formation of carbonate radicals, which benefits the generation of light-emitting intermediate 3-aminophthalate anions. Notably, the LDHs-improved H2O2–luminol CL signal is markedly restrained in the presence of ARS, which is assigned to the ARS-mediated occupation of the positively charged centres on the brucite-like layers and the inhibition of the formation of 3-aminophthalate anions. Thus, a facile CL method for ARS perception based on the suppression effect of ARS toward the LDHs-improved H2O2–luminol CL has been developed. This simple CL approach shows a limit of detection of 0.1 μM toward ARS and exhibits a linear response in the concentration range from 0.5 to 30 μM. In addition, the proposed method exhibits a high specificity toward ARS over other small molecules, metal ions or anions. Furthermore, the practical application of the proposed method for ARS sensing is evaluated with the dye wastewater samples.

The surface states of carbon nanodots (CDs) were engineered by controlling the chemical structure on the surface of the CDs, which play an important role in the chemiluminescence sensing properties of CDs towards peroxynitrite. Their application in monitoring exogenous and endogenous release of peroxynitrite in living cells is demonstrated.

Finding an efficient photosensitizer is crucial in ensuring a therapeutic effect of photodynamic treatment. Currently, screening of photosensitizers during photodynamic therapy is achieved by evaluating the total yield of singlet oxygen (1O2), rather than monitoring the formation dynamics of 1O2. 1O2-based chemiluminescence (CL) is a suitable method to directly monitor the generated amount of 1O2. Herein, the tetraphenylethene-sodium dodecyl sulfonate surfactant with aggregation-induced emission characteristics can remarkably amplify the intrinsic CL emission from 1O2 by integrating its micellar microenvironment with a CL energy acceptor effect in a cage-like structure. We present a new luminescence platform for the rapid screening of photosensitizers by monitoring the formation dynamics of 1O2 during photodynamic therapy. This study will not only be critical in optimizing the irradiation time during photodynamic therapy but also open a new door to the discovery of efficient photosensitizers.

The structural phase of micelles plays an important role in controlling the micellar performance. Despite the great developments of some advanced characterization techniques, it remains challenging to achieve fast and sensitive determination of micellar transitions in solution. Herein, a novel indicator system for micellar transitions was developed based on the micelle-mediated peroxyoxalate chemiluminescence that showed a sensitive response toward the changes of micellar morphologies. A peroxyoxalate derivative and a fluorophore were first coassembled into the hydrophobic cavities of micelles of the typical cationic surfactant cetyltrimethylammonium bromide (CTAB). A strong and rapidly falling chemiluminescence response was exhibited in spherical micelles as a result of the loose arrangement of CTAB molecules. By contrast, rodlike or wormlike micelles transformed from spherical micelles could induce a compact arrangement of CTAB molecules, leading to a weak chemiluminescence emission with a slow decay rate. The practicability and universality of the chemiluminescent indicator were demonstrated by determining the micellar transitions in a variety of surfactant solutions (ionic, nonionic, and polymeric). These findings open attractive perspectives for the practice of chemiluminescence technique in micelle characterization.

Layered nanomaterial has become a popular hierarchical material for amplifying chemiluminescence (CL) in recent years, mainly because of its ease of preparation and modification, large specific surface area, and high catalytic activity. In this review, we mainly discuss layered-nanomaterial-amplified CL systems based on graphene and its derivatives, layered double hydroxides, and clay. Detection mechanisms and strategies of layered-nanomaterial-amplified CL systems are provided to show the basic concepts for designing sensitive and selective sensing systems. Strategies for expanding the applications of layered-nanomaterial-amplified CL systems by combination with surfactants, quantum dots, organic dyes, and nanoparticles are introduced for the analysis of various analytes in real samples. The challenges and future trends of layered-nanomaterial-amplified CL systems are discussed at the end of the review. Graphical Abstract Schematic illustration of layered nanomaterial amplified chemiluminescence.

The current chemiluminescence (CL) probes for hydroxyl radical (•OH) are poorly selective owing to a non-specific redox reaction. To the best of our knowledge, there have not been established on the CL probes for •OH using the strong electrophilicity of •OH. In this work, an ultrastrong CL emission is initiated by electrophilic attack of •OH towards rhodamine B (RhB) on the surface of montomorillonite (MMT). The improved CL emissions are attributed to the oriented H-type aggregation of RhB molecules on the surface of MMT by π–π stacking interactions, resulting in an increase in π-electron density of aromatic ring of RhB. The high π-electron density of benzene ring could facilitate the attack of electrophilic •OH towards RhB. In addition, a novel CL probe for •OH with high selectivity and high sensitivity has been established using the electrophilic properties of •OH rather than its common redox properties. The applicability of the proposed CL probe is evaluated by detecting •OH in untreated and gentamicin treated mouse fresh plasma samples. Our findings provide a new strategy to improve the selectivity of CL sensor of •OH.

The oxygen states (O-states) of carbon quantum dots (CDs) play an important role, with regard to their optical properties and analytical applications. However, the rapid screening of O-states in CDs is still a great challenge, because of the complicated surface composition. In this study, it is found that the chemiluminescence (CL) intensity of prepared CDs in the presence of peroxynitrite (ONOO-) is proportional to the content of C-O group-related O-states. The related mechanism discloses that the O-state-dependent CL is due to the fact that abundant C-O functional groups in CDs with high O-states could facilitate the electron transfer of the produced smaller energy gaps for strong CL emission. Hence, ONOO--induced CL can be utilized as a facile probe for the rapid screening of O-states in CDs with some advantages, such as rapid response, low cost, and easy operation. Its practicability is verified by detecting the CL of phosphorus-doped CDs with variable phosphorus-doping contents. The content of C-O group-related O-states in sulfur-/phosphorus-doped CDs measured by the proposed CL probe is consistent with X-ray photoelectron spectroscopy (XPS) characterization. This strategy can also be extended to distinguish O-states in different types of nanoparticles by tuning the CL probe molecules.

The emergence of aggregation-induced emission (AIE) has opened up a new avenue for scientists. There is a great demand for the development of a new generation chemiluminescence resonance energy transfer (CRET) acceptors with AIE characteristics due to the aggregation-caused chemiluminescence (CL) quenching effect commonly observed in the conventional fluorophore CL acceptors at high concentrations. However, the systematical studies involving in AIE-amplified CL are still scarce. Herein, it is the first report that the gold nanocluster aggregates (a type of well-defined AIE molecules) are used to study their influence on the bis(2,4,6-trichlorophenyl) oxalate (TCPO)-H2O2 CL reaction. Interestingly, the AIE molecules in the diluted solution are unable to boost the CL signal of the TCPO-H2O2 system, but their aggregates display a strongly enhanced CL emission compared to their counterparts of fluorophore molecules, thanks to the unique AIE effect of gold nanoclusters. In comparison to rhodamine B with the aid of an imidazole catalyst, the detection limit of the gold nanocluster aggregate-amplified CL probe for H2O2 (S/N = 3) is low in the absence of any catalyst. Finally, the other two typical AIE molecules, Au(I)-thiolate complexes and 9,10-bis[4-(3-sulfonatopropoxyl)-styryl]anthracene (BSPSA), are investigated to verify the generality of the AIE molecule-amplified CL emissions. These results demonstrate effective access to highly fluorescent AIE molecules with practical applications in avoiding the aggregation-induced CL quenching at high concentrations, which can be expected to provide a novel and sensitive platform for the CL amplified detection.

In this work, carbon nanospheres (CNSs) were prepared with glucose through a hydrothermal synthesis method. Subsequently, a cetyltrimethylammonium bromide (CTAB) bilayer was used to modify the surface of the as-prepared CNSs (denoted as CTAB–CNSs). Interestingly, it was found that CTAB–CNSs could significantly amplify chemiluminescence (CL) emissions from some reactive oxygen species systems, including the Co(II)–H2O2–OH− system, ClO− system and ONOO− system. The CL intensity was proportional to the concentration of H2O2 in the Co(II)–H2O2–OH− system in a linear range of 5–1000 μM with a limit of detection of 2.6 μM (S/N = 3). The enhancement mechanism of CTAB–CNS-amplified CL from the Co(II)–H2O2–OH− system was investigated using the fluorescence spectra, CL spectrum, scavengers of reactive oxygen species, and UV-vis absorption spectra. The results indicated that the CTAB bilayer on the surface of CNSs could form a particular micelle microenvironment, facilitating the reaction between reactive intermediates and CNSs. Finally, this method has been successfully used to detect H2O2 in river water and lake water samples, and the recoveries were from 96 to 110%. The relative standard deviation (RSD) for nine repeated measurements was less than 5%.

In general, the chemiluminescence (CL) sensing of vitamin B-12 is achieved by determining Co(II) liberated from acidified vitamin B-12 by a luminol system. However, the luminol system for sensing vitamin B-12 has poor selectivity due to serious interference from other metal ions. In this study, as a novel CL amplifier of the Co(II)+H2O2+OH- ultra-weak CL reaction (Fenton-like system), dodecylbenzene sulfonate (DBS)-layered double hydroxides (LDHs) have been applied to the specific determination of vitamin B-12 by liberating Co(II). The CL intensity increased with increasing the concentration of vitamin B-12 in a wide range from 1.0 ng mL(-1) to 5 mu g mL(-1) with a detection limit of 0.57 ng mL(-1) (S/N=3). The proposed method has been successfully applied to determine vitamin B-12 in egg yolk with simple procedures, shorter time and higher selectivity. Recoveries from spiked real samples were 96-103%. The results of the proposed method for sensing vitamin B12 in real samples were agreed with those obtained by the standard inductively coupled plasma mass spectrometry (ICP-MS) method. To the best of our knowledge, this is the first report on the CL sensing of vitamin B-12 with high selectivity in the absence of luminol. (C) 2014 Elsevier B.V. All rights reserved.

In this study, Co(II)-EDTA-intercalated Mg-Al layered double hydroxides (LDHs) synthesized by anion exchange method were immobilized in a clear quartz tube to fabricate a novel chemiluminescence (CL) flow-through sensor. Interestingly, this simple micro-fabricated flow cell could greatly enhance the CL signals from the luminol-H2O2 reaction. The detection limit for H2O2 (S/N = 3) was 0.14 μM. Trace metal ions in the matrix had no effect because they were easy to complex with EDTA. The proposed sensor has been successfully applied to determine H2O2 in snow water samples with simple procedures, shorter response time and higher selectivity. The results demonstrated that this proposed method had great potential in chemical/biological sensing for H2O2 as well as for other oxidase-based reactions producing H2O2. To the best of our knowledge, this is the first report on the use of metal complex-intercalated LDHs for CL signal amplification.

In this study, the directional luminescent quantum dot (QD)-layered double hydroxide (LDH) assembly was fabricated by embedding the trace QDs onto the exterior surface of the organo-modified LDHs. It was found that this novel nanomaterial was able to extraordinarily improve an ultra-weak chemiluminescence (CL) emission from peroxynitrous acid (ONOOH). The enhanced CL emission was attributed to the electrostatic concentration of peroxynitrite (ONOO−) onto the orderly surface of the QD-organo-modified LDHs as well as the hydrophobic microenvironment of the organo-LDHs, facilitating the production of superoxide radical ( O2−) and hydroxyl radical ( OH). In addition, the CL intensity increased with increasing the concentration of nitrite in a wide range of 1.0–1000 μM with a detection limit of 0.3 μM (S/N = 3). Therefore, the proposed method was applied for the selective and sensitive detection of nitrite in sausage samples. Recoveries from spiked real samples were in the range of 96–103%. The results of the proposed method for sensing nitrite in real samples were agreed with those obtained by the standard spectrophotometric method.

In this work, based on electronic spinning resonance and chemiluminescence (CL) measurements, it is found that the reaction kinetics of Co(II)-triggered Fenton-like reaction is much faster than those of other transition metal ions, which facilitates the observation of the strong CL signals from Co(II). Utilizing the polymer-surfactant complexes (i.e., necklace model) to act as a novel CL microenvironment, a highly selective CL sensing system for the detection of Co(II) has been successfully fabricated based on the CL resonance energy transfer between the Fenton-like reaction and necklace model microenvironment-modulated carbon dots. Under optimized experimental conditions, this proposed CL system exhibits a stable response to Co(II) over a concentration range from 1.0 to 1000 nM with a detection limit as low as 0.67 nM. Finally, this system has been successfully used for the detection of Co(II) in HepG2 cells, and the results were agreed with those obtained by inductively coupled plasma mass spectrometry (ICP-MS) method.

In this work, we fabricate an oriented luminescent quantum dot (QD)-layered double hydroxide (LDH) nanocomposite material by the highly orderly and alternate assembly of trace CdTe QDs in dodecylbenzene sulfonate bilayer bunches on the organo-modified LDH exterior surfaces. Interestingly, the novel QD-LDH nanocomposites can remarkably amplify chemiluminescence (CL) of the luminol-H2O2 system, which is attributed to an inhibition of QD oxidation by H2O2, an increase in the radiative decay rate, and an inhibition in the nonradiative relaxation of QDs. In addition, a novel flow-through column-based CL resonance energy transfer is fabricated using luminol as energy donors and the solid luminescent QD-LDH nanocomposites as energy acceptors for signal amplification. The applicability of this flow-through column is evaluated by determining H2O2 using luminol-H2O2 CL system. The CL intensity exhibits a stable response to H2O2 over a concentration range from 0.5 to 60 μM with a detection limit as low as 0.3 μM. Finally, the proposed method has been successfully applied to detect H2O2 in snow samples, and the results agreed with those obtained by the standard spectrophotometric method. Our findings indicate that the new luminescent QD-LDH nanocomposite material would be used for high throughput screening of complex systems with different sized QDs.

We report a novel approach for preparation of networked gold nanoparticles (AuNPs) using reactive oxygen species (i.e., peroxymonocarbonate, HCO(4)(-)) as a novel reducing agent, along with nonionic fluorosurfactant (FSN) assistance. The formation mechanism of the networked AuNPs is demonstrated by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), UV-visible spectroscopy, powder X-ray diffraction (XRD) measurement and energy dispersive X-ray spectroscopy (EDS). In this case, HCO(4)(-) serves as a reducing agent for the preparation of the networked AuNPs, and further as a strong oxidizing agent attached to the surface of networked AuNPs, which can trigger the strong CL emission from luminol without the addition of H(2)O(2). In addition, FSN can control and stabilize the crystal morphology of the networked AuNPs, and improve the selectivity of the CL detection system for aminothiols. Finally, the networked AuNPs have been applied for ultrasensitive detection of aminothiols in human urine and plasma samples.

In this work, serving as supports in immobilizing luminol reagent, catalysts of luminol chemiluminescence (CL), and buffer solutions for the CL reaction, Mg-Al-CO3 layered double hydroxides (LDHs) were found to trigger luminol CL in weak acid solutions (pH 5.8). The silica sol–gel with glucose oxidase and horseradish peroxidase was immobilized in the first half of the inside surface of a clear quartz tube, and luminol-hybrid Mg-Al-CO3 LDHs were packed in the second half. Therefore, a novel CL flow-through biosensor for glucose was constructed in weak acid solutions. The CL intensity was linear with glucose concentration in the range of 0.005–1.0 mM, and the detection limit for glucose (S/N=3) was 0.1 μM. The proposed biosensor exhibited excellent stability, high reproducibility and high selectivity for the determination of glucose and has been successfully applied to determine glucose in human plasma samples with satisfactory results. The success of this work has broken the bottleneck of the pH incompatibility between luminol CL and enzyme activity.

There is currently great interest in developing chemiluminescence (CL) probes that can selectively detect peroxynitrite (ONOO(-)) in living cells. In comparison with other reactive oxygen species (ROS), ONOO(-) can spontaneously decompose into a series of radicals. Notably, the interaction of quantum dots (QDs) with oxidizing/reducing ROS radicals can generate a strong CL emission by electron-transfer annihilation. Herein, we report a novel CL probe that affords the ability to distinguish ONOO(-) from other ROS in living cells. ONOO(-) can activate luminescence of QDs in the absence of excitation source, effectively avoiding background noise and scattering of light from biological matrixes produced by in situ excitation; however, there is no response to other ROS including (1)O2, H2O2, (•)OH, O2(•-), and ClO(-). The outstanding selectivity of the present CL probe leads us to detect the exogenous release of ONOO(-) from 3-morpholinosydnonimine (SIN-1) in living cells. These results suggest that this present probe-based CL provides a promising platform for highly selective and sensitive detection of ONOO(-) in biological systems.

The interlamellar dodecylbenzene sulfonate (DBS) in layered double hydroxides (LDHs) can amplify an ultraweak chemiluminescence (CL) from Fenton-like reaction (Co(II) + H2O2 + OH–). The CL enhancem...

In this study, it was found that sodium dodecylbenzene sulfonate (SDBS)-modified LDHs can significantly enhance the chemiluminescence (CL) from the periodate-hydrogen peroxide (IO4–-H2O2) CL reaction. Using CL spectrum, powder X-ray diffraction measurements, scanning electron microscope images, transmission electron microscopy images, Fourier transform infrared spectroscopy, the quenchers for reactive oxygen species, and elemental analysis techniques, the enhancement mechanism of SDBS-modified LDHs on the IO4–-H2O2 CL was discussed in detail. The results showed that the adsorbed SDBS on the external surface of SDBS-modified LDHs made the disappearance of electrostatic repulsion between anionic surfactants and anionic CL reactants, resulting in the concentrating of anionic CL reactants on the adsorbed surfactant layers of SDBS-modified LDHs and the higher CL efficiency in LDH microenvironment. The success of this work expands currently limited applications of anionic surfactants in CL field.

It was found that CdTe semiconductor nanocrystals (NCs) can induce a great sensitized effect on chemiluminescence (CL) emission from peroxynitrous acid (ONOOH)-Na2CO3 system. CL spectra, fluorescence (FL) spectra, and the quenching effect of reactive oxygen species were used to investigate the CL reaction mechanism. The CL intensity was proportional to the concentration of nitrite in the range from 0.05 to 50 mu M. The detection limit (S/N = 3) was 0.024 mu M and the relative standard deviation (RSD) for five repeated measurements of 0.5 mu M nitrite was 4.2%. This method has been successfully applied to determine nitrite in well water samples with recoveries of 94.0-100.5%. This was the first work for direct (not inhibition effect) determination of analytes using semiconductor NCs-based CL sensor. (C), 2011 Elsevier B.V. All rights reserved.

In the last two decades nanoparticles have been widely applied to enhance chemiluminescence (CL). The morphology of nanoparticles has an important influence on nanoparticle-amplified CL. However, studies of nanoparticle-amplified CL focus mainly on the size and shape effects, and no attempt has been made to explore the influence of uniformity in nanoparticle-amplified CL processes. In this study we have investigated nanoparticle uniformity in the luminol-H2O2 CL system using layered double hydroxides (LDHs) as a model material. The results demonstrated that the uniformity of LDHs played a key role in CL amplification. A possible mechanism is that LDHs with high uniformity possess abundant catalytic active sites, which results in high CL intensity. Meanwhile, the sensitivity for H2O2 detection was increased by one order of magnitude (1.0 nM). Moreover, the uniform-LDH-amplified luminol CL could be applied to selective detection of glucose in human plasma samples. Furthermore, such a uniformity-dependent CL enhancement effect could adapted to other redox CL systems-for example, the peroxynitrous acid (ONOOH) CL system.

In this work, carbon nanodots were synthesized through a novel solvothermal route, and the effects of carbon nanodots on the ultraweak chemiluminescence (CL) reaction of hydrogen peroxide (H2O2) and sodium bisulfite (NaHSO3) were explored for the first time. It was found that the CL emission intensity of H2O2–HSO3– was significantly enhanced by carbon nanodots: about 60-fold increase in the CL intensity was obtained. The enhanced CL was induced by the excited-state carbon nanodots (CD*), which could be produced from the electron-transfer annihilation of positively charged carbon nanodots (CD•+) and negatively charged carbon nanodots (CD•–). Radical scavengers such as nitro blue tetrazolium chloride (NBT), sodium azide, thiourea, 5,5-dimethyl-1-pyrroline N-oxide, and ascorbic acid were used to study the intermediate species. The intermediate radicals generated during the reaction of H2O2 and NaHSO3, such as hydroxide radical (•OH), sulfate anionic radical (SO4•–), superoxide anionic radical (•O2–), and sul...

Nanomaterial-amplified chemiluminescence (CL) has become a growing area of interest in recent years. We review the development of nanomaterial-amplified CL systems and their applications in bioassays. We mainly focus on nanoparticles (gold, platinum, silver, bimetallic, semiconductor and magnetic). Furthermore, we discuss some critical challenges in this field and possible solutions to overcome these challenges.

In this work, different types of Mn-doped ZnS QDs were prepared and applied to study of the chemiluminescence reaction of hydrogen peroxide and periodate. The effects of the size of nanoparticles, shell protection and the stabilizing agents on chemiluminescence intensity were studied. The results indicated that the size of quantum dots was not the only factor to enhance the intensity of chemiluminescence system. Different stabilizing agents and the silica film protection will also influence the performance of the quantum dots in the chemiluminescence reaction. A CL spectrum was examined by using a series of high-energy cut-off optical filters and a possible mechanism of the CL was also proposed.

Chemiluminescence (CL) phenomenon of hydrogen peroxide with potassium permanganate in the presence of sodium hydrogen carbonate was reported. Effects of the surfactant on the CL system were investigated. Nonionic surfactants could effectively increase the CL signal. Radical scavengers and organic reagents such as nitro blue tetrazolium chloride (NBT), cytochrome c, sodium azide, ascorbic acid, thiourea, tert-butanol and dimethyl sulphoxide were used to study the emitting species. CL emission spectrum was recorded and the results showed that the maximal emission wavelengths of NaHCO3-H2O2-KMnO4 system were 440 and 634 nm. The mechanism was discussed based on electron spin resonance (ESR) spectra, fluorescence spectra and UV-vis absorption spectra. The addition of rhodamine B or uranine into this CL system enhanced the CL signal. It was due to part of the energy transfer from singlet oxygen and excited triplet dimers of two CO2 molecules to rhodamine B or uranine. The CL could be induced by excited rhodamine B or uranine.

The on-line incorporation of cloud point extraction (CPE) to flow injection analysis (FIA) was previously based on the use of a cotton-packed column to entrap the analyte-containing surfactant aggregates after salt-induced CPE, and then the preconcentrated analyte was eluted into a separate detection cell for subsequent chemiluminescence (CL) detection (via the peroxyoxalate CL reaction). In the work, the on-line CPE/FIA technique was improved by the following: (1) sample preconcentration and CL detection were both carried out directly inside the collection column, thus avoiding the decrease in detection sensitivity due to sample dispersion and dilution, and (2) CL detection was performed through the reaction between nitrite and hydrogen peroxide, which is compatible with aqueous samples and should allow for chemical excitation to occur more efficiently inside the collection column. In addition to more effective sample preconcentration, the CL detection of the entrapped analytes directly inside the collection column, i.e., a unique heterogeneous microenvironment in which analyte-containing surfactant aggregates were embedded within the densely packed filtering material, may also contribute to the overall increase in CL intensity (e.g., a CL enhancement factor of ca. 1000). Under optimum experimental conditions, the calibration curve was found to be linear for the CL detection of bilirubin (5 to 120 mu g L-1), the limit of detection (S/N = 3) was 1.8 mu gL(-1), and the R.S.D. was ca. 2.6% (n = 30) for 20 mu g L-1 bilirubin. Good agreements were obtained for the determination of total bilirubin in certified reference human serum samples between the present approach and an established clinical method. (c) 2007 Published by Elsevier B.V.

Chemiluminescence (CL) probes for reactive oxygen species (ROS) are commonly based on a redox reaction between a CL reagent and ROS, leading to poor selectivity toward a specific ROS. The energy-matching rules in the chemiluminescence resonance energy transfer (CRET) process between a specific ROS donor and a suitable fluorescence dye acceptor is a promising method for the selective detection of ROS. Nevertheless, higher concentrations of fluorescence dyes can lead to the intractable aggregation-caused quenching effect, decreasing the CRET efficiency. In this report, we fabricated an orderly arranged structure of calcein-sodium dodecyl sulfate (SDS) molecules to improve the CRET efficiency between ONOOH* donor and calcein acceptor. Such orderly arranged calcein-SDS composites can distinguish peroxynitrite (ONOO(-)) from a variety of other ROS owing to the energy matching in the CRET process between ONOOH* donor and calcein acceptor. Under the optimal experimental conditions, ONOO(-) could be assayed in the range of 1.0-20.0 μM, and the detection limit for ONOO(-) [signal-to-noise ratio (S/N) = 3] was 0.3 μM. The proposed strategy has been successfully applied in both detecting ONOO(-) in cancer mouse plasma samples and monitoring the generation of ONOO(-) from 3-morpholinosydnonimine (SIN-1). Recoveries from cancer mouse plasma samples were in the range of 96-105%. The success of this work provides a unique opportunity to develop a CL tool to monitor ONOO(-) with high selectivity in a specific manner. Improvement of selectivity and sensitivity of CL probes holds great promise as a strategy for developing a wide range of probes for various ROS by tuning the types of fluorescence dyes.

This review extensively covers information on chemiluminescence-detection systems for five reactive oxygen species, including superoxide radical, singlet oxygen, hydroxyl radical, hydrogen peroxide and peroxynitrite. We evaluate in detail the current state and the limitations of different chemiluminescence systems. We give some pointers to the likely directions of future developments and prospects.

Peroxynitrous acid (ONOOH) was produced by the on-line reaction of acidified hydrogen peroxide with nitrite in a flow system, and peroxynitrite (ONOO(-)) was generated from ONOOH in NaOH solution. A weak chemiluminescent (CL) emission was observed due to the production of singlet oxygen ( O(2)1) during the decomposition of ONOO(-). Bilirubin and its conjugate were found to enhance the CL emission of O(2)1 in a suitable micellar medium. For the first time, the feasibility of employing the present CL system for the sensitive and selective determination of total bilirubin contents in human serum was demonstrated and the results were compared with certified values. The present method showed a great improvement on overcoming bis(2,4,6-trichlorophenyl)oxalate CL highly insolubility in aqueous solution and exhibiting higher tolerance towards interferences than redox reaction of bilirubin with various oxidizing agents such as sodium hypochlorite and iodine. The recoveries of bilirubin were found to fall in the range between 95 and 108%. The detection limits (S/N=3) for bilirubin and its conjugate were determined to be 10 and 8ngml(-1), respectively. The relative standard deviations (R.S.D.) for the consecutive CL detection of a series of bilirubin (30mugl(-1)) and bilirubin ditaurite (25mugl(-1)) were 3.2 and 2.9% (n=11), respectively.

Peroxynitrous acid (ONOOH) was produced by the on-line mixing of acidified hydrogen peroxide with nitrite in a flow system. A strong chemiluminescent (CL) emission was observed when ONOOH reacted with carbonate without any special CL reagents. When cotton was present in the CL cell, the CL emission was enhanced significantly. The method was developed to determine nitrite, which showed a key improvement that any CL reagents and sensitizers were not used, resulting in better selectivity. The applicability of the present CL system was demonstrated for the sensitive and selective determination of nitrite in natural water samples without any special pretreatment. Good agreements were obtained for the determination of nitrite in tap and well waters between the present approach and a standard spectrophotometric method. The average precision was 4.6% (n = 7) and detection limit (S/N = 3) was 1.0 x 10(-7) M. Based on the CL spectrum, UV spectra, and dissolved oxygen measurement, a possible CL mechanism was proposed. ONOOH was an unstable compound in acidic solution and could be quenched into peroxynitrite (ONOO-) in basic solution. ONOO- reacted with CO2 to produce ONOOCO2-, which can rapidly decompose into (NO2)-N-. and (CO3-)-C-. radicals. In the presence of H+, (CO3-)-C-. radicals can protonate to bicarbonate radical (HCO3.). The recombination of HCO3. radicals and decomposition can lead to light emission. (C) 2004 Elsevier B.V. All rights reserved.

In the present work, a new flow-injection chemiluminescent (CL) method for the determination of nitrite has been proposed. In acidic medium, nitrite reacts with hydrogen peroxide to form peroxynitrous acid, which is an unstable compound in acidic solution and can be quenched into peroxynitrite in basic solution. During the decomposition of peroxynitrite a weak CL was observed. With the presence of ethyldimethylcetylammonium bromide (EDAB) and uranine, the CL intensity was enhanced significantly. This CL system was developed as a flow-injection method for the determination of nitrite. The CL intensity is proportional to the concentration of nitrite in the range from 1.0 x 10(-7) to 5.0 x 10(-5) M. The analytical frequency is 30 samples/h. The detection limit (S/N = 3) is 5.0 x 10(-8) M and the relative standard deviation for nine repeated measurements of 1.0 X 10(-6) M nitrite was 4.3%. The interferences of some cationic and anionic ions on the CL were studied. The anionic ions have almost no effect on the nitrite determination. After using a cation-exchange column as pre-treatment, the interferences of the cationic ions can be removed well. This method has been satisfactorily applied to determine nitrite in tap and well waters with recoveries of 94-106%. (C) 2002 Elsevier Science B.V. All rights reserved.

So-called confinement effects at the interface of nanomaterials could spring up unique properties in catalytical activities and optical amplifiers. There is apparently no good reason to disregard confinement effect-amplified chemiluminescence (CL). In this work, confinement effects were first introduced into CL field using cetyltrimethylammonium bromide (CTAB) bilayer aggregates confined at the interface of the CTAB-carbon dots, which were prepared by one-step microwave irradiation using glycerol as carbon source in the presence of CTAB. Interestingly, it was found that the CTAB bilayer confined at the interface of carbon dots can amplify H2O2 induced ultraweak CL emissions, such as the Co(II)-triggered Fenton-like reaction, the peroxynitrous acid (ONOOH) system, and the peroxymonocarbonate (HCO4(-)) system. The study of fluorescent properties of the as-prepared CTAB-carbon dots and the comparison with the CL efficiency of their analogues indicated that the CTAB bilayer confined in carbon dots could act as a special micelle microenvironment, helping the access of reactive intermediates to the central carbon core. Our findings opened up new possibilities in confinement-enhanced CL emissions.

Turn-on/off fluorescence and visual sensors through hydrogen bonding recognition have been clearly established in the literature. There is apparently no good reason to disregard hydrogen bonding-induced inactivation of chemiluminescence (CL). In this work, serving as novel CL catalyst and CL resonance energy transfer acceptor (CRET), layered double hydroxide (LDH) nanosheet colloids can induce a significant increase in the CL intensity of bis(2,4,6-trichlorophenyl) oxalate (TCPO)-H2O2 system. On the other hand, biogenic amines can selectively inhibit the CL intensity of the LDH nanosheet-TCPO-H2O2 system as a result of inactivation of photoluminescence LDH nanosheets through the displacement of O-H ⋯ O bonding by O-H ⋯ N bonding. In addition, histamine is used as a common indicator of food spoilage, and it is found that the CL intensity is linear with histamine concentration in the range of 0.1-100 µM, and the detection limit for histamine (S/N=3) is 3.2 nM. The proposed method has been successfully applied to trace histamine evolution of spoiled fish and pork meat samples, displaying a time-dependent increase in the biogenic amines levels in such samples.

In this work, we utilized the nonionic fluorosurfactant-capped gold nanoparticles (GNPs) as a novel chemiluminescence (CL) probe for the determination of trace bisphenol A. Bisphenol A can induce a sharp decrease in CL intensity from the GNP-Co(2+)-peroxymonocarbonate (HCO4(-)) system. Under the selected experimental conditions, a linear relationship was obtained between the CL intensity and the logarithm of concentration of bisphenol A in the range of 0.05-50 μM (R(2) = 0.9936), and the detection limit at a signal-to-noise ratio of 3 for bisphenol A was 10 nM. The applicability of the proposed method has been validated by determining bisphenol A in real polycarbonate samples with satisfactory results. The recoveries for bisphenol A in spiked samples were found to be between 94.4% and 105.0%. The relative standard deviation (RSD) for 12 repeated measurements of 0.5 μM bisphenol A was 2.2%. The proposed method described herein was simple, selective and obviated the need of extensive sample pretreatment.

In this work, Mg–Al CO 3 -layered double hydroxides (LDHs) were used as adsorbent materials for sodium dodecyl benzene sulfonate (SDBS) in aqueous solutions, the enriched SDBS can be directly detected by IO 4 − –H 2 O 2 chemiluminescence (CL) system. The commonly existing cations cannot be enriched by Mg–Al CO 3 -LDHs due to the structurally positively charged layers of LDHs, while other adsorbed anionic interferents had no effect on the IO 4 − –H 2 O 2 CL reaction. The corresponding linear regression equation was established in the range of 0.1–10 μM for SDBS. The detection limit at a signal-to-noise (S/N) ratio of 3 for SDBS was 0.08 μM. The relative standard deviation (RSD) for nine repeated measurements of 0.5 μM SDBS was 2.6%. This proposed method has been successfully applied to the determination of SDBS in river water samples. To the best of our knowledge, we have first time coupled the high enrichment capacity of LDHs towards anions with CL detection for analytes.

In this work, a universal chemiluminescence (CL) flow-through device suitable for various CL resonance energy transfer (CRET) systems has been successfully fabricated. Highly efficient CRET in solid-state photoactive organic molecules can be achieved by assembling them on the surface of layered double hydroxides (LDHs). We attribute these observations to the suppression of the intermolecular π-π stacking interactions among aromatic rings and the improvement of molecular orientation and planarity in the LDH matrix, enabling a remarkable increase in fluorescence lifetime and quantum yield of organic molecules. Under optimal conditions, using peroxynitrous acid-fluorescein dianion (FLUD) as a model CRET system, trace FLUD (10 μM) was assembled on the surface of LDHs. Peroxynitrous acid/nitrite could be assayed in the range of 1.0-500 μM, and the detection limit for peroxynitrous acid/nitrite (S/N = 3) was 0.6 μM. This CL flow-through device exhibited operational stability, high reproducibility, and long lifetime. While LDHs were immobilized in a flow-through device in the absence of FLUD, the detection limit for peroxynitrous acid/nitrite was 100 μM. On the other hand, FLUD at the same concentration can not enhance the CL intensity of peroxynitrous acid system. This fabricated CL flow-through column has been successfully applied to determine nitrite in sausage samples with recoveries of 98-102%. These satisfactory results demonstrated that our studies pave a novel way toward flow-through column-based CRET using solid-state organic molecules as acceptors for signal amplification.

In general, the reduction of disulfide bonds with tris(2-carboxyethyl)phosphine (TCEP) is performed using off-line operation, which is not only time-consuming but also vulnerable to the spontaneous re-oxidation of thiols during sample preparation and subsequent analysis procedures. To the best of our knowledge, there has been not any case on the on-line reduction for biological disulfides coupled with high performance liquid chromatography (HPLC). In this study, these obstacles are overcome by packing Zn(II)-TCEP complexes into a home-made column. The as-synthesized Zn(II)-TCEP complexes enable efficient reduction of disulfide bonds at pH 3.0. This acidic pH value was compatible with that of the mobile phase for HPLC separation of thiols and disulfides. Therefore, using fluorosurfactant-prepared triangular gold nanoparticles as HPLC postcolumn specific chemiluminescence (CL) reagents for thiols, the feasibility of the established on-line reduction column has been confirmed for the direct identification of both thiols and disulfides by incorporating this reduction column into a single chromatographic separation. Detection limits for these analytes range from 8.3 to 25.4 nM and the linear range in a log–log plot can comprise three orders of magnitude. Finally, the utility of this automated on-line reduction of disulfides-HPLC-CL system has been demonstrated for the reliable determination of thiols and disulfides in human urine and plasma samples.

An on-line solid phase extraction device combined with flow-through chemiluminescence monitoring was presented for the enrichment and determination of humic acid (HA) in water samples. The chemiluminescence principle was based on the enhancement effect of HA on the Ce(IV)/H(2)SO(4)-rhodamine 6G chemiluminescence system. For sample pretreatment, the on-line solid-phase extraction (SPE) material was packed into a cartridge which was then installed in the manifold. Experimental parameters including reagent concentration, flow rate and extraction time, were optimized. Under the optimized conditions, the relative standard deviation was 3.6% for determining 2 mg L(-1) HA standard solution and the detection limit was 3 μg L(-1). The proposed method was successfully applied to the determination of HA in the range of 0.1-35 mg L(-1). The results were validated by spike recovery experiments. The recovery was from 74.0% to 121%, which was good enough for the determination of HA in environmental waters.

In this work, a chemiluminescence (CL) reaction between hydrogen peroxide (H(2)O(2)) and sodium hydrosulfite (NaHSO(3)) was developed. Hydroxyl radical ((•)OH) and sulfite radical ((•)SO(3)(-)) were the main intermediates generated in the NaHSO(3)-H(2)O(2) CL system. Inhibition effects of radical scavengers such as thiourea, chloride ion, nitro blue tetrazolium chloride (NBT), and 5,5-dimethyl-1-pyrroline N-oxide (DMPO) indicated the existence of these two radicals. Singlet oxygen ((1)O(2)) and excited sulfur dioxide (SO(2)*) were emitting species involved in NaHSO(3)-H(2)O(2) CL system. (1)O(2) were confirmed by 1,4-diazobicyclo[2,2,2]octane (DABCO) and sodium azide (NaN(3)), which were specific (1)O(2) scavengers. In addition, electron spin resonance (ESR) spectra clearly show the existence of (1)O(2) and (•)OH. Alcoholic solvent, especially n-butanol, enhanced the ultraweak CL emission more than 40 times. The enhancing effect of alcoholic solvent on NaHSO(3)-H(2)O(2) CL system was ascribed to the formation of solvent cage, which can accelerate the reaction rate and protect the emitting species from quenching by water. The CL emission of the NaHSO(3)-n-butanol-H(2)O(2) system was measured by cutoff filters. The maximum wavelength was located around 490 nm, which belongs to (1)O(2). The wide peak from 400 to 600 nm is the characteristic peak of SO(2)*.

In this work, we utilize the triangular gold nanoparticles (AuNPs) prepared by trisodium citrate reduction of HAuCl(4) in presence of nonionic fluorosurfactant (FSN) as a novel chemiluminescence (CL) probe for the determination of captopril. Captopril can induce a sharp decrease in CL intensity from the triangular AuNPs-catalyzed luminol system. Under the selected experimental conditions, a linear relationship was obtained between the logarithm of CL intensity and the logarithm of concentration of captopril in the range of 23.0-920 nM, and the detection limit at a signal-to-noise ratio of 3 for captopril was 4.6 nM. The as-prepared triangular AuNPs were easier to synthesize, stable at a wider pH range and high ionic strength, and exhibited a high selectivity and an excellent sensitivity toward captopril. The applicability of the proposed method has been validated by determining captopril in commercial pharmaceutical formulations and human urine samples with satisfactory results. The recoveries for captopril in spiked samples were found to be between 95.0% and 103.5%. The method shows promise for routine control analysis of pharmaceutical preparations and human urine samples. Moreover, based on the CL spectra, UV-vis spectra and transmission electron microscope (TEM) measurements, a possible CL mechanism was proposed. The mechanism of high selectivity toward captopril is supposed to originate from the tight binding of the sulphydryl groups of captopril to the active site of the as-prepared triangular AuNPs, leading to oxygen-related radicals cannot easily be generated from H(2)O(2) on the surface of triangular AuNPs.

Our recent study demonstrates the synthesized triangular gold nanoparticles (AuNPs) by trisodium citrate reduction of HAuCl 4 in the presence of nonionic fluorosurfactant (FSN) could display stronger catalytic activity towards luminol-chemiluminescence (CL) than spherical AuNPs. Ultratrace aminothiols may cause a great decrease in CL intensity of the triangular AuNPs–luminol CL system. In this article, we utilize the as-prepared triangular AuNPs as novel postcolumn CL reagents to explore a simple high-performance liquid chromatography (HPLC)-CL method for the determination of low molecular weight aminothiols ( i.e. , cysteine, homocysteine, glutathione, cysteinylglycine and glutamylcysteine). The as-prepared triangular AuNPs were easier to synthesize, stable at a wider pH range and high ionic strength, and highly selective and sensitive towards reduced aminothiols. The detection limits at a signal-to-noise ratio of 3 for cysteine, homocysteine, glutathione, cysteinylglycine and glutamylcysteine were 0.016, 0.08, 0.1, 0.04 and 0.1 pmol, respectively. Recoveries from spiked urine and plasma samples were 95.7–104.3%. The applicability of the proposed method has been validated by determining these low molecular weight aminothiols in human urine and plasma samples with satisfactory results, and thus it will have great potential application in clinical diagnosis.

In this study, gold nanorods were firstly found to exhibit a tremendously higher catalytic activity towards luminol chemiluminescence (CL) than spherical gold nanoparticles. More importantly, ultra-trace aminothiols can cause a great CL decrease in the gold nanorod-catalyzed luminol system by the formation of Au–S covalent bonds on the ends of gold nanorods. Aminothiols can occupy the active sites of gold nanorods, and further interrupt the generation of the active oxygen intermediates. Other biomolecules including 19 standard amino acids, alcohols, organic acids and saccharides have no effect on gold nanorod-catalyzed luminol CL signals. Moreover, in order to evaluate the applicability and reliability of the proposed method, it was applied to the determination of glutathione in the cell extracts of Saccharomyces cerevisiae . Good agreements were obtained for the determination of glutathione in the cell extracts of S. cerevisiae between the present approach and a standard Alloxan method. The recoveries of glutathione were found to fall in the range between 96 and 105%. The calibration curve for glutathione was found to be linear from 0.05 to 100 nM, and the detection limit (S/N = 3) was 0.01 nM. The relative standard deviation (RSD) for five repeated measurements of 5.0 nM glutathione was 2.1%.

Peroxymonocarbonate (HCO 4 − ) was produced by the online reaction of bicarbonate with hydrogen peroxide. A strong chemiluminescence (CL) was observed when HCO 4 − reacted with AuCl 4 − without any special CL reagent. When bisphenol A (BPA) was added to AuCl 4 − –HCO 4 − CL system, the CL emission was inhibited significantly. This new CL system was developed as a flow-injection method for the determination of BPA. Under the optimum experimental conditions, the inhibited CL intensity was linearly related to the concentration of BPA from 0.3 to 80 μM ( R = 0.9958). The detection limit of BPA was 0.08 μM. The relative standard deviation for 12 repeated measurements of 1.0 μM BPA was 2.9%. The interferences of some cationic ions can be removed by an online cation-exchange column. The applicability of the present CL system was demonstrated for the sensitive and selective determination of BPA in real samples (mineral water bottle, baby bottle, beverage bottle and polycarbonate container). Based on the CL spectrum, UV–visible adsorption spectra, and the quenching effect of reactive oxygen species scavengers, a possible CL mechanism was proposed.