Luminol Chemiluminescence Reaction Research Articles

Low-temperature subcritical water dechlorination composites of waste PVC/coal fly ash with powerful sensing activity for chemiluminescent detection of acetamiprid and imidacloprid

Pesticide residues in agricultural products are serious threat to people's health. Real-time monitoring of pesticides residues in the environment and agricultural products posed challenges to sustainable methods with high analytical performance for pesticide detection. Herein, waste PVC/coal fly ash (the mass ratio of PVC and coal fly ash was 4:1) was dechlorinated in subcritical water at low temperature to achieve nearly 100 % dechlorination of PVC and obtain carbon-based composite materials (CM-Fe/Al/Si-dPVC) with strong sening activity. For CM-Fe/Al/Si-dPVC, CFe bonding resulted in strong electron migration, and nano/μm SiO2 and Al2O3 doping in the layered polyene C matrix provided large specific surface area, and silicon hydroxyl created good heterogeneous catalytic interfaces. CM-Fe/Al/Si-dPVC could strongly trigger luminol chemiluminescence (CL) reaction and produce intense CL signals. Neonicotinoid pesticides (acetamiprid and imidacloprid) bonded with CM-Fe/Al/Si-dPVC through coordination chelation and hydrogen bonding, which shielded the catalytic active site and increased the Fermi level of system, thus quenching CL reaction. Inspired by these, a cheap CL assay was constructed for detecting neonicotinoids combinations of acetamiprid and imidacloprid (NICs). The detection limits of NICs were 0.7 ng/L. Satisfactory recoveries were obtained for real agricultural products and environmental samples. The results of life cycle evaluation (LCA) revealed that the strategy had significantly small global warming potential (GWP). This work presented a sustainable method with environmental benefits for the detection of neonicotinoids, and also opened up new way for the recycling of organic solid wastes.

Droplet array with microfluidic concentration gradient (DA-MCG) for 2-dimensional reaction condition screening

Droplet microfluidic technology can use each microdroplet as a microreactor, which has the advantages of low reagent dosage, less cross contamination, and fast reaction time. Combining concentration gradient generation with droplet formation and capture to form a two-dimensional reaction condition screening platform (including reactant concentration and reaction time) is expected to broaden the application range of microfluidic screening. In this work, a microfluidic chip that can dynamically generate and capture microdroplets and form static microdroplet array was designed and fabricated. An optimized Christmas tree structure by adjusting the horizontal channel length ratio was used to generate a chemical concentration gradient while obtaining a uniform outlet flow rate, forming a droplet array with different concentrations. The performance of droplet array with microfluidic concentration gradient (DA-MCG) was verified using sodium fluorescein as a model reagent. The chromogenic reaction of NaOH and phenolphthalein, and luminol chemiluminescence reaction were used to verify the two-dimensional screening ability of DA-MCG. The results indicated that the DA-MCG has the potential to be applied in the field of multi-dimensional drug screening.

Room-Temperature Synthesized Iron/Cobalt Metal-Organic Framework Nanosheets with Highly Efficient Catalytic Activity toward Luminol Chemiluminescence Reaction.

Two-dimensional (2D) iron/cobalt metal-organic framework nanosheets (Fe/Co-MOF NSs) were synthesized via the cooperative self-assembly reaction of Fe3+/Co2+ and terephthalic acid at room temperature. The as-prepared 2D Fe/Co-MOF NSs display superior performance in catalysis of the chemiluminescence (CL) reaction between luminol and H2O2. The CL spectrum, UV-vis absorption spectroscopy, radical scavenger experiments, and electron spin resonance (ESR) spectroscopy are utilized to research the possible CL mechanism of the luminol-H2O2-Fe/Co-MOF NSs system. All results indicate that Fe/Co-MOF NSs present outstanding peroxidase-like activity and could catalyze H2O2 to produce 1O2, O2·-, and ·OH, which could react rapidly with the luminol anion radical and result in strong CL. With the highly efficient CL of the luminol-H2O2-Fe/Co-MOF NSs system, a sensitive sensor for the detection of dopamine (DA) is developed based on the inhibitory effect of DA on the CL intensity. Good linearity over the range of 50-800 nM is achieved with a limit of detection of 20.88 nM (S/N = 3). This research demonstrates that 2D Fe/Co-MOF NSs is a highly effective catalyst for luminol CL reaction and has great application potential in the CL field.

A turn-on chemiluminescent assay for alkaline phosphatase using two-dimensional Fe-centered metal-organic frameworks as the signaling probe.

Alkaline phosphatase (ALP) is an essential enzyme involved in cell phosphorus metabolism. Developing sensitive and accurate ALP quantitative assays is significant. In this study, a turn-on chemiluminescence (CL) analysis platform for the detection of ALP activity in human serum was established based on two-dimensional (2D) Fe-centered metal-organic frameworks with 1,3,5-benzene tricarboxylic acid as ligands (denoted as 2D Fe-BTC). The 2D Fe-BTC as the signaling probe reacts with ascorbic acid forming reduced Fe-BTC which catalyzes the luminol CL reaction producing a strong CL signal. The 2D Fe-BTC-based luminol CL reaction exhibited good CL responses when the concentration of ascorbic acid was in the range of 5-500nM. By employing magnesium ascorbyl phosphate (MAP) as the substrate which can be hydrolyzed by ALP to generate ascorbic acid, a turn-on CL assay for the detection of ALP was established. Under optimal conditions, as low as 0.00046UL-1 of ALP could be sensitively detected with a linear range of 0.001-0.1UL-1. ALP in human serum can be detected after a simple dilution process without any other pretreatment.

Automated and label-free detection of HIV DNA via digital microfluidics-chemiluminescence analysis

Automated and sensitive detection of nucleic acid is crucial for reliable and safe disease diagnostics because the minimum manual operation can effectively avoid sample contamination and infection risk. Herein, a sensitive, label-free and automated method was developed for detecting trace DNA by integrating digital microfluidics (DMF) with chemiluminescence (CL) detection. DMF can automatically manipulate discrete droplets. Taking advantage of sensitive and simple CL detection, DMF-CL integration can automatically and sensitively detect HIV DNA via the preset pathway. To further improve the sensitivity, on-chip exponential amplification reaction (EXPAR) was explored to produce large quantities of double-stranded DNA (dsDNA) in the presence of HIV DNA. Then, SYBR Green I (SG) intercalated into dsDNA to generate singlet oxygen upon light irradiation, which in situ oxidized potassium ferrocyanide into potassium ferricyanide. Finally, the CL reaction of potassium ferricyanide and luminol ensured the label-free, reliable and specific detection of HIV DNA in the range of 10 pM to 2 nM. Saving time-consuming and laborious manual operations, the DMF-CL integration greatly reduced the reagent consumption and avoided the contamination of DNA sample as well. Therefore, DMF-CL offers a promising and useful technology for developing automated and reliable biosensing and bioanalysis.

PVC dechlorination residues as new peroxidase-mimicking nanozyme and chemiluminescence sensing probe with high activity for glucose and ascorbic acid detection

Polyvinyl chloride (PVC) dechlorination residues urgently need to be used to improve PVC recycling efficiency. Herein, PVC dechlorination residues were used for visual colorimetry and chemiluminescence (CL) sensing for the first time. It was found that the dechlorination residues of PVC and iron chips treated by subcritical water showed excellent peroxidase-mimicking activity and could catalyze enzyme substrate 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation to produce blue product. Based on this, residues colorimetric analysis was developed to detect hydrogen peroxide in the range of 3.2 × 10−8–9.5 × 10−5 M and glucose in the range of 8.9 × 10−6–9.2 × 10−4 M. The detection limits were estimated to be 4.5 × 10−9 M for hydrogen peroxide and 6.8 × 10−7 M for glucose, respectively. The kinetic investigation of enzymatic reaction confirmed that the simulated enzyme activity of the residues was much stronger than that of the previously synthesized nanocomposite (The Km and Vmax of the residue system with TMB as the substrate were 0.298 mM and 207.3 × 10−8 M S−1, respectively). In addition, the residues could alone trigger luminol CL reaction to produce strong CL signal with no need for oxidant, and the residues CL analysis was developed for detection of ascorbic acid (AA) in the range of 1.5 × 10−12 M to 7 × 10−8 M with the detection limit of 0.32 pM. The results affirmed that the residues were fantastic colorimetric and CL sensing material, which not only provided vital reference for residues applications in other sensing assays, but also was important for construction of the sensing platforms using wastes.

A new NiS nanoparticle-enhanced chemiluminescence method for determination of cephalexin in pharmaceuticals and spiked human serum.

It has been reported that NiS nanoparticles (NPs) can markedly enhance light emission from the chemiluminescence (CL) reaction of luminol-O2 (λmax = 425 nm). Additionally, it was shown that cephalexin (CEF) could further increase the intensity of light emitted from the NiS NPs-luminol-O2 CL reaction. Inspired by these findings, we aimed to develop a new and straightforward CL method for the determination of CEF. A calibration graph over the range 1.00 × 10-6 to 4.00 × 10-5 mol L-1 was established. The limit of detection of the CL method was 8.00 × 10-7 mol L-1 . The coefficient of variation of the CL method was 2.20% (n = 6) for the measurement of 6.00 × 10-6 mol L-1 CEF. NiS NPs were produced by exploiting the precipitation method and identified using several spectroscopic approaches. The proposed CL method was successfully used to measure CEF in some pharmaceutical products and in spiked human serum. The chemical mechanism governing the CL reaction was briefly explained.

Imaging of Chemical Kinetics at the Water-Water Interface in a Free-Flowing Liquid Flat-Jet.

We present chemical kinetics measurements of the luminol oxidation chemiluminescence (CL) reaction at the interface between two aqueous solutions, using liquid jet technology. Free-flowing liquid microjets are a relatively recent development that have found their way into a growing number of applications in spectroscopy and dynamics. A variant thereof, called flat-jet, is obtained when two cylindrical jets of a liquid are crossed, leading to a chain of planar leaf-shaped structures of the flowing liquid. We here show that in the first leaf of this chain, the fluids do not exhibit turbulent mixing, providing a clean interface between the liquids from the impinging jets. We also show, using the example of the luminol CL reaction, how this setup can be used to obtain kinetics information from friction-less flow and by circumventing the requirement for rapid mixing by intentionally suppressing all turbulent mixing and instead relying on diffusion.

Ascorbic acid as an alternative coreactant for luminol reaction and sensitive chemiluminescence determination of ascorbic acid in soft drinks

Ascorbic acid can serve as an efficient coreactant for luminol chemiluminescence (CL) reaction. An observable CL emission is produced when mixing ascorbic acid with luminol in an alkaline condition. The CL signal is further dramatically enhanced by cobalt(II) ions. This CL system was exploited as a new method for direct determination of ascorbic acid with a flow injection mode. A good linear response is acquired between the CL signal and ascorbic acid concentration in 5.0–1000.0 ng/mL range with a detection limit of 1.3 ng/mL. The relative standard deviations are 2.3% for intra–day (n = 11) and 3.7% for inter–day (n = 3) by parallel determination of 0.5 μg/mL ascorbic acid solution. The method has good selectivity for ascorbic acid since no obvious responses are observed for a variety of inorganic ions and biological substances. The practicability of the method has been demonstrated by the analysis of ascorbic acid in some soft drinks.

Natural catalyst for luminol chemiluminescence: application to validate peroxide levels in commercial hair dyes.

Here, we report a hydrothermally treated green leaves (Moringa oleifera) extract exploited as an efficient and highly sensitive catalyst to catalyze the chemiluminescence (CL) reaction of luminol. In the absence of enhancer, this green and hydrothermally treated catalyst was found to significantly enhance the CL intensity ~3.5-fold compared with the traditionally used K3 Fe(CN)6 catalyst. The structure and surface morphology of the catalyst was elucidated using X-ray photoelectron spectroscopy, scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. The synergistic effect of the catalyst in the CL reaction was systematically investigated in the presence of hydrogen peroxide using ultraviolet-visible and CL spectroscopy. Studies showed that the sensitivity of the catalyst could be amplified by adjusting several parameters such as pH of the medium and concentrations of the base and luminol. The sensitivity of the novel-type catalyst was examined through the validation of hydrogen peroxide levels in commercial hair dye samples. Markedly, the catalyst displayed ultrasensitivity to hydrogen peroxide as the limit of detection of hydrogen peroxide using this catalyst was determined to be 0.02 μM under optimized conditions. In general, the proposed inexpensive, ecofriendly, and nontoxic catalyst could enable the determination of hydrogen peroxide for diverse analytical applications.

Ultrasensitive and practical chemiluminescence sensing pesticide residue acetamiprid in agricultural products and environment: Combination of synergistically coupled co-amplifying signal and smart interface engineering

Practical detection of single-component pesticide residue at ultra-low concentrations in agricultural products and environment is very important for assessment of environmental risks and protection of human health. Herein, a practical and highly sensitive chemiluminescence (CL) sensing acetamiprid in agricultural products and environmental media was constructed based on the synergistic co-catalysis of graphene oxide (GO)/gold nanoparticles (AuNPs) nanocomposites for luminol CL reaction and the smart interface engineering. ss-DNA could inhibit co-catalysis of GO/AuNPs for luminol CL reaction. Once acetamiprid was added, aptamer conformation changed in dimension and synergistically catalytic amplification signal of GO/AuNPs was restored significantly. The limit of detection was 8.9 pM. High sensitivity could be due to strong signal amplification from synergistic catalysis of GO/AuNPs for CL reaction and perfect regulation of composite interface by DNA dimension. Moreover, the used GO/AuNPs could be stably stored for six months, which was superior to previously reported AuNPs (only half a month). The analysis exhibited excellent selectivity for acetamiprid. The detection results for real samples confirmed reliability in practical application. This analysis is an extremely useful method for monitoring pesticide residues in environment and agricultural products. Synergetic co-catalysis of GO/AuNPs and ingenious interface engineering provide important ideas for other biosensors.

Magnetic covalent organic framework immobilized gold nanoparticles with high-efficiency catalytic performance for chemiluminescent detection of pesticide triazophos

Covalent organic frameworks (COFs) are considered to be a promising support material for catalyst due to their highly ordered porous structure. Here, a core-shell structured Fe3O4 magnetic covalent organic framework (Fe3O4@COF) was synthesized and employed to provide basic sites for immobilization of gold nanoparticles (AuNPs). The AuNPs was in-situ immobilized on the shell of Fe3O4@COF via a citrate reducing method. The Fe3O4@COF-AuNP had convenient magnetic separability and exhibited excellent mimicking peroxidase-like activity in catalyzing chemiluminescence (CL) reaction of luminol with hydrogen peroxide (H2O2). With acetylcholine chloride (ACh) as substrate of acetylcholinesterase (AChE), a CL method was exploited for sensitive detection of organophosphorus pesticide triazophos due to its irreversible inhibiting effect on the AChE activity and subsequently influences the production of H2O2 under the condition of choline oxidase (ChOx). This method gave a good linearity for triazophos in the range of 5.0–300.0 nmol L−1, and a limit of detection (LOD) of 1 nmol L−1 was acquired. The applicability of this method was verified by the determination of triazophos in different spiked vegetable samples.

A sensitive chemiluminescence detection approach for determination of 2,4-dinitrophenylhydrazine derivatized aldehydes using online UV irradiation – luminol CL reaction. Application to the HPLC analysis of aldehydes in oil samples

Aldehydes are toxic carbonyl compounds that are identified in various matrices surrounding us. For instance, aldehydes could be formed during the cooking and frying of foods which affects the food quality and safety. Derivatization is a must for the determination of aldehydes as they lack intrinsic chromophoric groups. 2,4-Dinitrophenyl hydrazine (DNPH) is the most used derivatizing reagent for aldehydes and the formed hydrazones could be determined by either HPLC-UV or LC-MS. However, UV detection is non-sensitive, and the MS equipment is expensive and not widely available. Thus, herein we report a smart chemiluminescence (CL) detection method for the DNPH aldehydes derivatives. These derivatives are supposed to possess photosensitization ability due to the presence of strong chromophoric structures; nitrobenzene and phenyl hydrazone. Upon their UV irradiation, singlet oxygen is found to be produced which then converts the DNPH-aldehyde derivative into hydroperoxide. Next, the hydroperoxide reacts with luminol in an alkaline medium producing a strong CL. An HPLC system with online UV irradiation and online reaction with luminol followed by CL detection was constructed and used for the determination of aldehydes after their derivatization with DNPH. The developed method showed excellent sensitivity with detection limits down to 1.5–18.5 nM. The achieved sensitivity is superior to that obtained by HPLC-UV and LC-MS detection methods for DNPH-aldehydes derivatives. Additionally, our approach is an chemiluminogenic where the DNPH reagent itself does not produce CL which is an excellent advantage. The method was applied successfully for the determination of aldehydes in canola oil samples using simple liquid-liquid extraction showing good recovery (87.0–106.0%), accuracy (87.2–106.6), and precision (RSD≤10.2%). After analysis of fresh and heated oil samples, it was demonstrated that heating of oil, even for short time, strongly elevated the level of their aldehydes' content. At last, it was found that the results of the analysis of aldehydes in oil samples using the proposed method perfectly matched those obtained by a reference LC-MS method.

A novel luminol-based chemiluminescence method for detecting acetylcholine

Aim. To develop а new simple non-enzymatic method for the determination of acetylcholine (ACh) by the chemiluminescent reaction of luminol under conditions of the enzymatic hydrolysis of acetylcholine (pH 8.5).Experimental part. The method proposed is based on the perhydrolysis reaction of ACh by the excess ofhydrogen peroxide with the formation of peracetic acid. The latter was further determined by the activation effect of the luminol chemiluminescent oxidation reaction in the presence of hydrogen peroxide. The analytical signal was the summary luminescence (Σ) registered within certain time.Results and discussion. The pH range of the analytically applicable system was from 8.2 to 8.5. The effect of ACh + H2O2 incubation period on the reaction progress was also studied. The increase of the incubation period enhanced the sensitivity of the method (the limit of detection (LOD)), but because of practical reasons (especially the detection speed) and practical experience the incubation period was set to 30 min. The linear dependence was observed in the acetylcholine chloride concentration range of (0.8 – 2.8) × 10-4 mol/L. While determining acetylcholine chloride in the concentration range of (1.1 – 2.2) × 10-4 mol/L the relative standard deviation (RSD) did notexceed 3 % ((X – μ) × 100 %/μ = –0.5…+0.5 %). The Limit of Quantitation (LOQ, 10S) was 7.7 × 10-5 mol/L.Conclusions. A new non-enzymatic kinetic method for the chemiluminescent determination of ACh in aqueous solutions and the pharmaceutical formulation Acetylcholinchlorid Injeel® has been proposed. This method is simple, fast, inexpensive, and thus appropriate for the routine ACh quality control in the laboratories of hospitals, pharmaceutical industries and research institutions.Key words: acetylcholine; chemiluminescence method

A novel luminol chemiluminescence induced by photoexcited ketones: A selective determination method for acetone in wastewater

It has been recently confirmed that photoexcited ketones such as acetone promote the chemiluminescence (CL) reaction of luminol and its analog, L-012. Using this finding, a selective determination method for acetone was developed herein based on HPLC separation, online UV irradiation, and subsequent luminol CL detection. Various conditions, including the type of luminol reagent, the use of organic solvents as eluent modifiers, and the reaction pH, were investigated to elucidate the CL reaction mechanism. The results showed that the CL reaction of luminol is caused by an acetone ketyl radical produced from the photoexcited acetone. The performance of the novel acetone determination method was evaluated by its application in water quality assurance in water treatment plants. The method detection limit and the method quantification limit of acetone were 0.03 and 0.08 µM, respectively. A linear range was obtained in the concentration range of 0.1–200 µM. The range of recovery in the wastewater and seawater samples (n = 5) fortified with 5.0 µM acetone was 87–108%. These results demonstrate that the new luminol CL system is useful for its sensitivity and selectivity.

Determination of folic acid by capillary zone electrophoresis with indirect chemiluminescence detection.

A capillary electrophoresis method with on-line inhibited chemiluminescence (CL) detection was first used to determine folic acid (FA). This method was established based on the quenching effect of FA on the CL reaction of luminol with a Ag(iii) complex in alkaline medium. The separation was conducted with a 20.0 mM sodium borate buffer containing 1.0 mmol L−1 luminol. Under optimized conditions, FA was baseline separated and detected in less than 10 min. The limit of detection of FA was 1.3 mg L−1, with a linear range of 5.0–150.0 mg L−1 (r = 0.9953). The RSD value was 2.8% for intra-day precision and 5.4% inter-day precision. The recoveries of the standard addition of tablets and human urine ranged from 90.3% to 107.5% and from 82.0 to 105.7%, respectively. The proposed method was successfully applied to determine FA contents in commercial pharmaceutical tablets and human urine samples. Results suggested that this method was simple and robust.

Luminol chemiluminescence reaction: Optimization by image analysis method and use in distinguishing human hemoglobin from potassium hexacyanoferrate(III) by addition of ascorbic acid

The luminol chemiluminescence reaction (luminol reaction hereinafter) is used to detect trace amounts of blood at a crime scene. In this study, luminol chemiluminescence was recorded with a smartphone and image analysis was performed to optimize the luminol reaction for use in distinguishing chemiluminescence produced by whole blood from that by iron(III) ions. The video file was analyzed by the image analysis software ImageJ and a two-dimensional chemiluminescence intensity vs. time graph was created. When luminol reagent that is composed of a mixture of 0.4%(w/v) luminol dissolved in 1.0%(w/v) sodium hydroxide aqueous solution and 1.0%(w/v) hydrogen peroxide aqueous solution (6:1) was used, chemiluminescence duration was increased in whole blood sample, whereas that in potassium hexacyanoferrate(III) sample was extremely short, namely, a spike-like peak was generated. Furthermore, when ascorbic acid was added to potassium hexacyanoferrate(III) in the stoichiometric ratio of 0.58 mol or higher to 1.0 mol of iron(III) ion, the false-positive result produced by iron(III) ions was suppressed. From the above results, by optimizing the composition of luminol reagent, it became possible to distinguish chemiluminescence due to whole blood from that due to potassium hexacyanoferrate(III) on the basis of the difference in chemiluminescence pattern. It was also suggested that the addition of ascorbic acid could eliminate false-positive results produced by potassium hexacyanoferrate(III).

One‐step synthesis of cationic gold nanoclusters with high catalytic activity on luminol chemiluminescence reaction

AbstractThe present study reports a one‐step synthesis method for the preparation of cationic gold nanoclusters (Au NCs). Polyethyleneimine (PEI), a positively charged hyperbranched polyamine, was selected as the capping reagent. Glutathione showed a synergistic effect on the formation of the small size of cationic Au NCs. The prepared cationic Au NCs have a size less than 2 nm and carry a positive charge in solution with pH less than 11. The cationic PEI–Au NCs‐triggered luminol chemiluminescence (CL) reactions showed slow and intense CL profiles. The maximum CL intensity can be obtained within 10 min and the CL signal maintained almost the same within 30 min. A linear increase of CL intensity was observed in the presence of an increasing concentration of cationic Au NCs ranging from 0.030 μM to 15 μM. The linear response of the cationic Au NCs in the CL reaction and the glow‐type CL profile make the proposed CL reaction have broad application prospects in the field of biological analysis and CL imaging.

A novel peroxidase/oxidase mimetic Fe-porphyrin covalent organic framework enhanced the luminol chemiluminescence reaction and its application in glucose sensing.

A Fe-porphyrin covalent organic framework (Fe-PorCOF) was prepared through a postmodification strategy and characterized using different techniques. Fe-PorCOF exhibits an inherent peroxidase/oxidase mimetic catalytic activity and sharply accelerates chemiluminescence (CL) reactions between luminol and hydrogen peroxide (H2 O2 ) or dissolved oxygen (O2 ) under alkaline conditions. The catalytic role was attributed to a significant increase in production of reactive oxygen species. Using the imminent peroxidase mimetic catalytic activity of Fe-PorCOF, a new CL method was developed for determination of H2 O2 over a linear range from 0.01 to 10.0 μmol·L-1 and with a limit of detection of 5.3 nmol·L-1 . The combination of the peroxidase mimetic catalytic activity of Fe-PorCOF with the catalytic activity of glucose oxidase on glucose oxidation presents a sensitive CL method for glucose assay. The linear range and the detection limit for glucose were 0.05-8.0 μmol·L-1 and 4.0 nmol·L-1 , respectively. The practicability of this method was assessed by determination of glucose in human sera. As a peroxidase/oxidase mimetic, Fe-PorCOF is easy to prepare and exhibits good catalytic efficiency in the luminol reaction. We believe that this strategy will promote the development of a CL field with functional COFs as a catalyst.

In situ encapsulation of horseradish peroxidase in zeolitic imidazolate framework-8 enables catalyzing luminol reaction undernear-neutral conditions for sensitive chemiluminescence determination of cholesterol.

HRP@ZIF-8 nanocomposite was prepared by in situ encapsulation of horseradish peroxidase (HRP) in the frame of zeolitic imidazolate framework-8 (ZIF-8) with a simple one-pot method. The HRP@ZIF-8 nanocomposite displays outstanding thermal stability and efficiently catalyzes the chemiluminescence (CL) reaction of luminol with hydrogen peroxide (H2O2) under near-neutral pH condition (pH 7-8). This CL system has a good response to H2O2 with a linear range of 0.1-100.0μmolL-1. The limit of detection (LOD) is 0.06μmolL-1 H2O2. By marriage with cholesterol oxidase, cholesterol is determined with a linear range from 0.1 to 100.0μmolL-1 and a LOD of 0.04μmolL-1. The relative standard deviations (RSD) are 1.7% and 2.5%, respectively, in 11 repeated measurements of 50.0μmolL-1 solutions of H2O2 and cholesterol, indicating excellent precision of the method. The method shows good selectivityand has been applied to the determination of total cholesterol in real serum samples. No significant difference has been observed between the results obtained by this method and thecholesterol oxidase-peroxidase coupling method. Graphical abstract Schematic presentation of in situ one-pot synthesis of horseradish peroxidase@zeolitic imidazolate framework-8 (HRP@ZIF-8) nanocomposite and chemiluminescence determination of cholesterol with HRP@ZIF-8 catalyzing luminol-H2O2 system.