A chemiluminescence (CL) based assay is described for the determination of the environmental pollutant 2-hydroxyfluorene (2-HOFlu) which is found to inhibit the CL of a system composed of the ...G-quadruplex/hemin complex (a DNAzyme), H.sub.2O.sub.2, and luminol. The G-rich aptamer PW17 is transformed to a potassium(I)-stabilized G-quadruplex-hemin complex which displays peroxidase-like activity to catalyze the oxidation of luminol by H.sub.2O.sub.2 which is accompanied by strong blue CL emission. On addition of 2-HOFlu, it will participate in the G-quadruplex DNAzyme-mediated oxidation by H.sub.2O.sub.2. As a result, CL intensity is decreased. The difference in CL intensity (DELTAI) before and after addition of 2-HOFlu serves as the signal for its quantitation. In water of pH 9.0, a linear relationship is found for the 1 nM to 1 muM concentration range, with a 0.2 nM detection limit. The assay is highly selective over other fluorene derivatives. It was successfully applied to the determination of 2-HOFlu in spiked lake water samples. The method is rapid, cost-effective and convenient. Conceivably, it has a wide scope in that it may be applied to other target pollutants for which G-quadruplexes are available.
A sandwich-configuration electrochemiluminescence (ECL) immunosensor based on Au star@BSA-Luminol nanocomposites for ultrasensitive determination of human chorionic gonadotropin (HCG) has been ...developed. In this work, nanostructured Polyaniline hydrogels (Pani) decorated with Pt nanoparticles (Pani/Pt) were utilized to construct the base of this immunosensor, greatly increasing the amount of loaded capture antibodies (Ab1) via linkage reagent glutaraldehyde (GA). The used conducting Pani/Pt nanocomposites possessed the unique features, such as large surface area, high electron transfer speed and favorable electrocatalytic activities of hydrogen peroxide, which offered a prominent platform for this sandwich-sensor and acted as efficient ECL signal amplifier also. Furthermore, we employed horseradish peroxidase (HRP) to block the nonspecific binding sites instead of commonly used bovine serum albumin (BSA), which further amplified the signal of luminol in the present of hydrogen peroxide (H2O2). In addition, Au star@BSA nanocomposites with excellent water solubility, low-toxicity and great biocompatibility were prepared and used to immobilize HCG detection antibodies (Ab2) and luminescent material luminol. Then, the above-synthetized Luminol-Au star@BSA-Ab2 complex was attached to the modified sensor by sandwiched immunoreactions. Under the optimized conditions, the proposed immunosensor exhibited a sensitive detection of HCG in a wide linear range from 0.001 to 500mIUmL−1 with a detection limit of 0.0003mIU/mL (S/N = 3). All the results indicated that such a sandwiched HCG immunosensor exhibited favorable ECL analytical performance. This developed method may be potentially used to recognize other clinical protein and display a novel ideal to construct an immunosensor.
•A sandwich-configuration ECL immunosensor for human chorionic gonadotropin was developed.•Polyaniline hydrogels decorated with Pt nanoparticles were used to construct the base.•Au star@BSA nanocomposites were prepared to immobilize HCG detection antibodies and luminol.•The proposed immunosensor exhibited favorable ECL analytical performance to HCG determination.•This developed method may be potentially used to recognize other clinical protein.
Dual signal amplification of CL is developed to detect vanillin based on its catalyzing the dissociation of H2O2 into active •OH and O2•− radicals and the stabilizing function of β-CD.
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•Vanillin can catalyze the dissociation of H2O2 into •OH and O2•− radicals effectively.•CL of luminol-H2O2 was enhanced greatly by catalyzed and stabilized function of vanillin and β-CD.•The proposed CL sensor for vanillin is rapid, simple and is applied in various foods.•CL imaging of vanillin was obtained, which can be discerned by naked eyes.•The method can be used to detect not only vanillin but also ethyl vanillin.
Among various chemiluminescence (CL) systems, luminol-H2O2 system is used extensively due to its cheapness and sensitivity. Herein, 4-hydroxy-3-methoxybenzaldehyde, known as vanillin, was firstly found to be able to catalyze H2O2 very efficiently to produce •OH and O2•−, which can be used to enhance the CL of luminol-H2O2 as Co+. In alkaline aqueous solution, vanillin catalyzed the dissociation of H2O2 into active •OH and O2•− radicals and accelerated luminol-H2O2 reaction to emit strong CL signal. Combining the stabilizing function of β-CD, CL intensity of luminol-H2O2 was enhanced further. Thus, dual-signal amplification of luminol-H2O2 chemiluminescence based on the catalyzing function of vanillin and the stabilizing function of β-CD was proposed and its mechanism was explored deeply in the manuscript. Interestingly, vanillin is a highly prized flavor compound broadly used as food additive, however, the excessive intake of vanillin is harmful to human and thus the determination of vanillin is very important. On the basis of the luminol-β-CD-H2O2/vanillin reaction, a low-cost, rapid and simple CL sensor has been established to detect vanillin. The sensor was able to detect vanillin in the range of 1.0 μM ∼ 75 μM with a detection limit of 0.89 μM (S/N = 3). It can also be used for CL imaging detection with satisfactory results.
Peroxidases are widely used as catalysts in chemiluminescence (CL) reaction because of their excellent catalytic activity and various selectable species, such as horseradish peroxidase (HRP), sweet ...potato peroxidase (SPP) and soybean peroxidase (SbP). They have been employed in many different CL systems for the determination of hydrogen peroxidase (H2O2), nucleic acid, protein and so on. In this paper, the application of peroxidases in the most commonly used luminol-H2O2 CL system was reviewed from two aspects of horseradish peroxidase (HRP) and some anionic peroxidases. Thereinto, some enhancers used into HRP-catalyzed luminol-H2O2 CL system for higher sensitivity and lower detection limit were discussed according to their classification. The employment of some anionic peroxidases such as SPP and SbP in luminol-H2O2 CL system was also presented. The addition of some specific enhancers into anionic peroxidase catalyzed luminol-H2O2 system could lead to an increased light intensity and a relatively long-term stable signal. The mechanism of all these enhanced luminol-H2O2 CL reaction and the foundation of their analytical application were provided and reviewed in detail. Finally, combined with the magnetic beads or nanoparticles as well as other technologies, the characteristics of peroxidase-based luminol-H2O2 CL system were summarized.
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•The peroxidase-catalyzed luminol-H2O2 CL systems were reviewed according to the category of peroxidases.•The addition of enhancers into the CL systems improved the sensitivity and lowered the detection limit of the analytes.•Peroxidase-based CL systems contributed to the development of immunoassay with higher sensitivity and simpler device.
A novel Co(L)(H2O)2 (1) was obtained by hydrothermal method and it exhibited a 1D chain with exposed carboxyl groups, the unique coordination mode made it have unusual physical and chemical ...stability. Meanwhile, 1 showed peroxidase-like and weak oxidase-like activity. 1 as a peroxidase mimic enzyme had an excellent affinity for the substrates luminol and H2O2. Compared with HRP, 1 had catalytic activity in a wide pH range and showed the best catalytic activity at pH 7.4. Meanwhile, the catalysis process of 1 was reversible and recyclable, and the catalytic activity remained stable after different pH and temperatures and long-time storage. Based on the inhibition of glutathione on luminol-H2O2-MOF 1 chemiluminescence signal, a chemiluminescence method for the determination of glutathione has been proposed with high sensitivity and selectivity and had been applied for detecting glutathione in cell lysate with satisfactory results.
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•A novel Co (Ⅱ)-based MOF material with double enzyme mimetic activity was synthesized.•The unique coordination mode made Co-MOF have unusual physical and chemical stability.•The Co-MOF had favorable catalytic activity in a wide pH range.•A CL sensing method for glutathione was developed using the luminol-H2O2-Co-MOF system under neutral condition.
A dual signal-amplified sandwich electrochemiluminescence (ECL) immunosensor was fabricated for trace detection of procalcitonin (PCT). CeO.sub.2-Au@Pt composed of sea urchin-like Au@Pt nanoparticles ...coated on CeO.sub.2 hollow nanospheres was immobilized on electrode surface to electrochemically catalyze H.sub.2O.sub.2 to produce a large number of superoxide anion (O.sub.2.sup.*-). The immunosensor was prepared by linking the capture antibody on immobilized CeO.sub.2-Au@Pt with heptapeptide (HWRGWVC), which could maintain the activity of the antibody. The prepared Au star@BSA was used to bind abundant luminol for labeling the secondary antibody (Ab.sub.2). Upon the sandwich-typed immunoreactions, the O.sub.2.sup.*- could react with the introduced luminol on the immunosensor surface to produce strong ECL intensity. With an outstanding linear detection range and a low detection limit of 17 fg/mL, the ECL immunosensor permitted ultrasensitive detection of PCT at a low H.sub.2O.sub.2 concentration and demonstrated its high application potential in the clinical assay. Graphical abstract
Due to the ultra-weak and instantaneous chemiluminescence (CL) of luminol–H2O2 system, developing new catalysts to dramatically enhance and produce persistent CL emission is crucial. In this study, ...the Cu-metal-organic frameworks (Cu–MOFs) with flower morphology converted from Cu-based metal-organic gels (Cu–MOGs) could catalyze luminol–H2O2 system, exhibiting persistent CL. The possible mechanism of this persistent emission of luminol was attributed to the gradual generation of OH˙, O2˙− and 1O2 in Cu–MOFs–catalyzed luminol–H2O2 system. In addition, OH˙ and O2˙− were continuously recombined into singlet oxygen on the surface of Cu–MOFs which further prolonged the duration time of the CL leading to the persistent emission, due to the longer lifetime of 1O2 compared to OH˙ and O2˙−. Furthermore, based on the high-intensity emission of Cu–MOFs–catalyzed luminol–H2O2 system, the strategy for sensitive response to quercetin was established with good linearity within the range of 0.05–1.2 μM and a detection limit of 49.7 nM. This study provides a new idea for developing persistent CL catalysts.
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•To the best of our knowledge, it is the first example of Cu–MOFs as persistent CL catalysts in luminol–H2O2 system.•The inherent catalytic activity of Cu–MOFs allowed the continuous production of three radicals (OH˙, O2˙− and 1O2).•Recombination mechanism: OH˙ and O2˙− recombined into 1O2 on the surface of Cu–MOFs and further prolonged the CL emission.•The high-intensive Cu–MOFs–luminol–H2O2 CL system was successfully applied to quantify quercetin.
Water-soluble forms of α-tocopherol (TP) as an effective antioxidant were obtained by encapsulating it into nanoparticles (NPs) of amphiphilic copolymers of N-vinylpyrrolidone with triethylene glycol ...dimethacrylate (CPL1-TP) and N-vinylpyrrolidone with hexyl methacrylate and triethylene glycol dimethacrylate (CPL2-TP) synthesized by radical copolymerization in toluene. The hydrodynamic radii of NPs loaded with TP (3.7 wt% per copolymers) were typically ca. 50 or 80 nm depending on copolymer composition, media, and temperature. Characterization of NPs was accomplished by transmission electron microscopy (TEM), IR-, and sup.1H NMR spectroscopy. Quantum chemical modeling showed that TP molecules are capable to form hydrogen bonds with donor groups of the copolymer units. High antioxidant activity of both obtained forms of TP has been found by the thiobarbituric acid reactive species and chemiluminescence assays. CPL1-TP and CPL2-TP effectively inhibited the process of spontaneous lipid peroxidation as well as α-tocopherol itself. The ICsub.50 values of luminol chemiluminescence inhibition were determined. Antiglycation activity against vesperlysine and pentosidine-like AGEs of TP water-soluble forms was shown. The developed NPs of TP are promising as materials with antioxidant and antiglycation activity and can be used in various biomedical applications.
A novel, simple and efficient chemiluminescence system has been developed for the determination of monoamine neurotransmitters and metabolites. By using the Ag (III)-luminol chemiluminescence system ...as a detector, a high performance liquid chromatography chemiluminescence method (HPLC-CL) was established and used to detect seven monoamine neurotransmitters. Under the optimized conditions, the detection limits (3S/N) of epinephrine (E), levodopa (l-DOPA), dopamine (DA), serotonin (5-HT), 3-methoxy-4-hydroxyphenylglycol (MHPG), 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxypentylacetic acid (5-HIAA) were 20.0 μg dm−3,15.0 μg dm−3, 15.0 μg dm−3, 8.0 μg dm−3, 2.0 μg dm−3, 2.0 μg dm−3 and 3.0 μg dm−3, respectively. Moreover, they were well within the linear range of 50–1000 μg dm−3, 50–1000 μg dm−3, 50–1000 μg dm−3, 25–1000 μg dm−3, 5–25 μg dm−3, 5–25 μg dm−3 and 10–30 μg dm−3, respectively. The average recovery varied between 84.82% and 110.4%. The method has the attributes of simplicity, high sensitivity, and high efficiency. The sensitization and inhibition mechanisms for luminol-Ag(HIO6)25–- analytes CL system were proposed by CL spectra and free-radical capture experiment.
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•We present a novel, sensitive and liable HPLC-CL method for the determination of seven MNTs in human serum.•Luminol-Ag(HIO6)25– system was first used in the HPLC-CL method for monoamine neurotransmitters and metabolites analysis.•The sensitization and inhibition mechanisms for Luminol-Ag(HIO6)25–-analytes CL system were proposed.
L-012, a luminol-based chemiluminescent (CL) probe, is widely used in vitro and in vivo to detect NADPH oxidase (Nox)-derived superoxide (O₂ ⁻) and identify Nox inhibitors. Yet understanding of the ...free radical chemistry of the L-012 probe is still lacking. We report that peroxidase and H₂O₂ induce superoxide dismutase (SOD)-sensitive, L-012-derived CL in the presence of oxygen. O₂ ⁻ alone does not react with L-012 to emit luminescence. Self-generated O₂ ⁻ during oxidation of L-012 and luminol analogs artifactually induce CL inhibitable by SOD. These aspects make assays based on luminol analogs less than ideal for specific detection and identification of O₂ ⁻ and NOX inhibitors.
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