Direct determination of horseradish peroxidase encapsulated in liposomes by using luminol chemiluminescence.

Horseradish peroxidase (HRP) encapsulated in liposomes was directly detected by using luminol chemiluminescence (CL) with H2O2 without lysis of liposomes. At a low concentration of H2O2, the initial rate of HRP-catalyzed luminol CL in liposomes was slower than that of HRP-catalyzed luminol CL in a lipid-free bulk solution. The decrease in the initial rate of the CL reaction in liposomes was due to the membrane permeation of luminol and H2O2. At a high concentration of H2O2, the initial rate of the CL reaction in liposomes was the same as that in a lipid-free bulk solution. The CL measurement conditions in both a lipid-free bulk solution and in liposomes were optimized in the concentrations of luminol and H2O2 by measuring the CL response curves, in which only one peak appeared and the CL intensity was maximal. The CL intensity observed in HRP-catalyzed luminol CL in liposomes was a factor of seven greater than that observed in a lipid-free bulk solution. The CL intensity was dependent on the amount of HRP-encapsulated liposomes used. The detection limit in the direct detection of HRP encapsulated in liposomes was sensitive by a factor of 3 compared with that in HRP-catalyzed luminol CL in a lipid-free bulk solution.     

An ultrasensitive chemiluminescence immunosensor for PSA based on the enzyme encapsulated liposome

A highly sensitive chemiluminescence immunosensor for the detection of prostate-specific antigen (PSA) was developed based on a novel amplification procedure with the application of enzyme encapsulated liposome. Horseradish peroxidase (HRP) encapsulated and antibody-modified liposome acts as the carrier of a large number of markers and specific recognition label for the amplified detection of PSA. In the detection of PSA, the analyte was first bound to the specific capture antibody immobilized on the microwell plates, and then sandwiched by the antibody-modified liposomes encapsulating HRP. The encapsulated markers, HRP molecules were released by the lysis of the specifically bound liposomes in the microwell with Triton X-100 solution. Then, the analyte PSA could be determined via the chemiluminescence signal of HRP-catalyzed luminol/peroxide/enhancer system. The “sandwich-type” immunoassay provides the amplification route for the PSA detection in ultratrace levels. The CL emission intensity exhibits dynamic correlation to PSA concentration in the range from 0.74 pg/ml to 0.74 μg/ml with readily achievable detection limit of 0.7 pg/ml.     

Effect of the luminol signal enhancer selection on the curve parameters of an immunoassay and the chemiluminescence intensity and kinetics

In the present study, three luminol signal enhancers {4-methoxyphenol, 4-hydroxybiphenyl and 4-(1H-pyrrol-1-yl)phenol} were utilized in the chemiluminescence (CL) substrate solution of horseradish peroxidase (HRP). The latter was applied in a heterogenous enzyme immunoassay that has been previously described. The employment of these molecules greatly affected important assay parameters, such as detection limit and the range of the calibration curve and the results were compared with those obtained from other two similar enhancers that have been described from our group. Practically, the use of a novel enhancer, even if this is a slightly changed 4-substituted phenol derivative, can affect assay properties so dramatically, one can assume that another substrate/enzyme system was applied. Furthermore, the use of different luminol signal enhancers in the luminol/HRP/H₂O₂ system affected not only the intensity of the obtained signal, which is well known, but also its kinetics. It was monitored that the stronger intensity was combined with a more rapid decrease of the CL signal.     

增强辣根过氧化物酶催化鲁米诺化学发光反应的新型增强剂四苯硼钠

报道了新型增强剂四苯硼钠对过氧化物酶催化鲁米诺－过氧化氢发光反应的增强作用，建立了流动注射化学发光测定或辣过氧化物酶（ＨＲＰ）的新体系。用该体系测定ＨＲＰ线性范围为１．０×１０－１２×１．２×１０－１３ｍｏｌ／Ｌ；检测限为０．６×１０－１３ｍｏｌ／Ｌ。对０．６×１０－１３ｍｍｏｌ／Ｌ的 ＨＲＰ进行１１次平行测定，相对标准偏差为 １． ５％。     

Gold nanorod-catalyzed luminol chemiluminescence and its selective determination of glutathione in the cell extracts of Saccharomyces cerevisiae

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%.     

A new chemiluminescence method for the determination of nickel ion

A new chemiluminescence (CL) phenomenon described as the second-chemiluminescence (SCL) was observed and a strong CL signal was detected, when Ni(II) ion was injected into the mixture after the end of the reaction of potassium permanganate with alkaline luminol. The possible CL mechanism is proposed based on the kinetic curve of the CL reaction, CL spectra, UV-vis spectra and some other experiments. A flow-injection analysis for the determination of nickle(II) ion has been developed, based on the catalysis of nickel(II) ion on the CL reaction between potassium manganate produced on-line and luminol under alkaline condition. Under the optimum conditions, the SCL intensity is linear with the concentration of nickel(II) ion in the range of 8.0-200.0 microg l-1 and 0.2-2.0 mg l-1. The R.S.D. was 4.5% for 11 determinations of 250 microg l-1 nickel(II) ion and the detection limit (3sigma) for nickel(II) ion was 0.33 microg l-1. The method was applied to determine nickel(II) ion in synthetic samples with satisfactory results.     

Highly sensitive microfluidic competitive enzyme immunoassay based on chemiluminescence resonance energy transfer for the detection of neuron‐specific enolase

A microfluidic competitive enzyme immunoassay based on chemiluminescence resonance energy transfer (CRET) was developed for highly sensitive detection of neuron‐specific enolase (NSE). The CRET system consisted of horseradish peroxidase (HRP)/luminol as a light donor and fluorescein isothiocyanate as an acceptor. When fluorescein isothiocyanate‐labeled antibody binds with HRP‐labeled antigen to form immunocomplex, the donor and acceptor are brought close each other and CRET occurs in the immunocomplex. In the MCE, the immunocomplex and excess HRP–NSE were separated, and the chemiluminescense intensity of immunocomplex was used to estimate NSE concentration. The calibration curve showed a linearity in the range of NSE concentrations from 9.0 to 950 pM with a correlation coefficient of 0.9964. Based on a S/N of 3, the detection limit for NSE determination was estimated to be 4.5 pM, which is two‐order magnitude lower than that of without CRET detection. This assay was applied for NSE quantification in human serum. The obtained results demonstrated that the proposed immunoassay may serve as an alternative tool for clinical analysis of NSE.     

Chemiluminescence flow system for the determination of sulfite

A novel chemiluminescence(CL) flow system for sulfite is described based on electrostatically immobilized luminol on an anion exchange column. Sulfite is detected by the CL reaction with luminol bleeding from the column by hydrolysis. The calibration graph is linear in the range 3 × 10^–7 to 1 × 10^–5 mol/L, and the detection limit is 1 × 10^–7 mol/L. Interfering metal ions co-existing in sample solutions could be effectively eliminated on-line by an upstream cation exchanger. A complete analysis could be performed in 1 min with a relative standard deviation of less than 5%. The system could be reused for over 50 h and has been applied successfully to the determination of sulfur dioxide in air.     

Chemiluminescence biosensor chip based on a microreactor using carrier air flow for determination of uric acid in human serum

A chemiluminescence biosensor on a chip coupled to a microfluidic system and a microreactor is described in this paper. The chemiluminescence biosensor measured 25 x 75 x 6.5 mm in dimension, and was readily produced in an analytical laboratory. The sol-gel method is introduced to co-immobilize horseradish peroxidase (HRP) and luminol in the microreactor, and to immobilize uricase in the enzymatic reactor. The main characteristic of the biosensor was to introduce air as the carrier flow instead of the more common solution carrier for the first time. The uric acid was determined by a chemiluminescent (CL) reaction between the hydrogen peroxide produced from the enzymatic reactor and luminol under the catalysis of HRP in the microreactor. The linear range of the uric acid concentration was 1 to 100 mg L(-1) and the detection limit was 0.1 mg L(-1) (3sigma).     

毛细管电泳免疫化学发光检测鼠血管平滑肌细胞中zmol骨形成蛋白-2

近年来,结合毛细管电泳的免疫分析研究在不断加强.特别是毛细管电泳免疫激光诱导荧光(CEIA-LIF)检测由于具有较高的灵敏度而十分引人注目.常文保等用CEIA-LIF检测雌三醇,检出限为31.6ng/L,可用于血清和尿样分析.Kennedy等用芯片CEIA-LIF检测了鼠胰腺细胞中的胰岛素,     

New bienzymatic strategy for glucose determination by immobilized-gold nanoparticle-enhanced chemiluminescence

Bienzymatic biosensor for the determination of glucose by flow injection chemiluminescence (CL) detection was proposed. Hybrids of gold nanoparticles (GNPs) and chitosan were chosen as the immobilization matrix of glucose oxidase (GOD) and horseradish peroxidase (HRP) to fabricate the biosensors with silane-pretreated glass microbeads. After the enzyme catalyzing oxidation of glucose in GOD biosensor, the produced H₂O₂ flowed into HRP biosensor to react with luminol. The doped GNPs in chitosan were found to enhance the classical CL reaction of luminol-H₂O₂-HRP. The CL enhancement was investigated in detail by CL and UV-visible spectrum. Under the optimized experimental conditions, glucose could be determined in a linear range from 0.01 to 6.0 mmol/L with a detection limit of 5.0 μmol/L at 3σ. The accuracy of the proposed method was examined by detecting the glucose level in four clinical serum samples from hospital. The proposed method provides a new alternative to determine glucose. Supported by the Natural Science Foundation of Shandong Province (Grant No. Q2007B03), the Doctoral Fund of Qingdao University of Science and Technology (Grant No. 0022141), and the National Natural Science Foundation of China (Grant No. 20775038)     

Determination of phenol by flow-injection with chemiluminescence detection based on the hemin-catalysed luminol-hydrogen peroxide reaction

This study established a novel flow injection (FI) methodology for the determination of phenol in aqueous samples based on luminol chemiluminescence (CL) detection. The method was based on the inhibition that phenol caused on the hemin-catalysed chemiluminescence reaction between luminol and hydrogen peroxide in alkaline solution. Optimum conditions and possible mechanisms have been investigated. The linear range was 2.0×10(-9) to 4.0×10(-7)gmL(-1) for phenol. The proposed method is sensitive with a detection limit of 4.0×10(-10)gmL(-1). The relative standard deviation for 11 measurements was 2.3% for 1.0×10(-7)gmL(-1) phenol. The method was applied for the determination of phenol in waste water samples. The results obtained compared well with those by an official method.     

Gold nanoparticles based chemiluminescent resonance energy transfer for immunoassay of alpha fetoprotein cancer marker

In this paper, we report a new strategy of chemiluminescence resonance energy transfer (CRET) by using gold nanoparticles (AuNPs) as efficient long-range energy acceptor in sandwich immunoassays. In the design of CRET system, we chose the highly sensitive chemiluminescence (CL) reaction of luminol and hydrogen peroxide catalysed by horseradish peroxidase (HRP) because the CL spectrum of luminol (λ(max) 425 nm) partially overlaps with the visible absorption bands of AuNPs. On the basis of CRET strategy, we developed a sandwich immunoassay of alpha fetoprotein (AFP) cancer marker. In immunoassay, two antibodies (anti-AFP-1 and anti-AFP-2) were conjugated to AuNPs and horseradish peroxidase (HRP), respectively. The sandwich-type immunoreactions between the AFP (antigen) and the two different antibodies bridged the donors (luminol) and acceptors (AuNPs), which led to the occurrence of CRET from luminol to AuNPs upon chemiluminescent reaction. We observed that the quenching of chemiluminescence signal depended linearly on the AFP concentration within a range of concentration from 5 to 70 ng mL(-1) and the detection limit of AFP was 2.5 ng mL(-1). Our method was successfully applied for determination of AFP levels in sera from cancer patients, and the results were in good agreement with ELISA assays. This approach is expected to be extended to other assay designs, that is, using other antibodies, analytes, chemiluminescent substance, and even other metallic nanoparticles.     

Sensitive determination of sub-nanogram amounts of rutin by its inhibition on chemiluminescence with immobilized reagents

An interesting inhibitory effect of rutin on the chemiluminescence (CL) reaction between luminol and periodate was reported, and this effect was used for the determination of rutin in medicine and human urine. The CL reagents, luminol and periodate, were both immobilized on an anion-exchange column. The CL signal produced by the reaction between luminol and periodate, which were eluted from the column through water injection, was decreased in the presence of rutin. Rutin was sensed by measuring the decrement of CL intensity, and which was observed to be linear over the logarithm of 0.1-30 ngml(-1) rutin concentration range, and the limit of detection was 0.03 ngml(-1) (3sigma). At a flow rate of 2.0 mlmin(-1), both sampling and washing could be performed in 0.5 min with a relative standard deviation of less than 3.0%. The method proposed offered reagent-less procedures and remarkable stability in the determination of rutin, and could be easily reused over 80 h. The method proposed was applied successfully in the determination of rutin in pharmaceutical preparations and monitoring the excretion of rutin in human urine.     

Ag(Ⅲ)配合物-鲁米诺化学发光体系用于文拉法辛的测定

Ag(Ⅲ)配合物在碱性介质中可氧化鲁米诺产生化学发光.实验发现,抗抑郁药物文拉法辛对该化学发光体系有显著的增敏作用.据此,结合流动注射技术,建立了化学发光测定文拉法辛的新方法.在优化条件下,方法的线性范围为0.1～2.0 mg·L-1,检出限(S/N=3)为0.05 mg·L-1,回收率为96％ ～ 105％,相对标准...     

Sensitive detection of tumor marker CA15-3 in human serum by capillary electrophoretic immunoassay with chemiluminescence detection

A new and sensitive non-competitive immunoassay (IA) for tumor marker carbohydrate antigen 15-3 (CA15-3) by CE coupling with ECL detection has been developed. This method is based on luminol-H(2)O(2 )reaction catalyzed by horseradish peroxidase (HRP). The optimum CE separation and CL detection conditions were investigated. After the non-competitive immunoreaction, the free HRP-labeled CA15-3 antibody (Ab*) and the bound Ab*-antigen (Ab*-Ag) complex were separated in a separation capillary and then catalyzed the CL reaction of luminol and H(2)O(2 )in a reaction capillary following the separation capillary. The calibration curve based on the peak areas of Ab*-Ag complex plotted against the concentrations of CA15-3 is in the range of 0-250 U/mL with a correlation coefficient of 0.9983 and the detection limit is 0.035 U/mL (S/N = 3). The response for five consecutive injections of 125 U/mL CA15-3 resulted in RSDs of 0.83% and 3.1% for the migration time and the peak area, respectively. The method was successfully used for the quantification of CA15-3 in human sera obtained from healthy persons and from patients with breast cancer.     

Analytical assessment of the oscillating chemical reactions by use chemiluminescence detection

This paper introduces the chemiluminescence (CL) detection in oscillating reaction-based determinations using the analyte pulse perturbation technique, a straightforward and expeditious approach to deriving quantitative analytical information from oscillating chemical reactions. The behavior of the H(2)O(2)-KSCN-CuSO(4)-NaOH oscillating system in the presence of luminol was examined by using the proposed detection method and the classical potentiometric technique. Some analytical and practical aspects of both detection systems are discussed. A new analytical method for the determination of vitamin B(6) based on the sequential perturbation produced by different amounts of this substance on the oscillating chemical system was also developed in order to assess the potential of CL detection for routine analyses. The calibration curve thus obtained was linear over the range 0.5-2.0 mumol of vitamin B(6), and the precision and throughput were also quite good (3.04% as RSD and nine samples h(-1), respectively). The proposed method was validated by determining the vitamin in pharmaceutical preparations.     

Chemiluminescence assay for uric acid in human serum and urine using flow-injection with immobilized reagents technology

A novel chemiluminescence (CL) flow sensor for the determination of uric acid in human urine and serum has been developed by using controlled-reagent-release technology. The reagents involved in the chemiluminescence (CL) reaction, luminol and periodate, are immobilized on anion-exchange resin packed in a column. After injection of water, chemiluminescence generated by released luminol and periodate in alkaline media is inhibited in presence of uric acid. By measuring the decreased chemiluminescence (CL) intensity the uric acid is sensed. The decreased response is linear in the 5.0-500.0 ng mL(-1) range, with a detection limit of 1.8 ng mL(-1). The flow sensor showed remarkable operational stability and could be easily reused for over 80 h with sampling frequency of 100 h(-1). The proposed sensor was applied to the determination of uric acid in human urine and serum, and monitoring metabolic uric acid in human urine with RSD less than 3.0%.     

Peroxidase-catalysed luminol chemiluminescence method for the determination of glutathione

A luminol chemiluminescence (CL) method was developed for the determination of glutathione (GSH). GSH was indirectly determined by measuring the amount of hydrogen peroxide formed during the Cu(II)-catalysed oxidation of GSH with oxygen. The amount of hydrogen peroxide formed was continuously measured using the Arthromyces ramosus peroxidase-catalysed luminol CL reaction. The CL intensities at maximum light emission were linearly correlated with the concentration of GSH over the range 7.5 x 10(-7)-3.0 x 10(-5) M. The detection limit for GSH was about 10 times better than that of the spectrophotometric method using Ellman reagent.     

Chemiluminescence flow system for the determination of sulfite

A novel chemiluminescence(CL) flow system for sulfite is described based on electrostatically immobilized luminol on an anion exchange column. Sulfite is detected by the CL reaction with luminol bleeding from the column by hydrolysis. The calibration graph is linear in the range 3 × 10^–7 to 1 × 10^–5 mol/L, and the detection limit is 1 × 10^–7 mol/L. Interfering metal ions co-existing in sample solutions could be effectively eliminated on-line by an upstream cation exchanger. A complete analysis could be performed in 1 min with a relative standard deviation of less than 5%. The system could be reused for over 50 h and has been applied successfully to the determination of sulfur dioxide in air. Received: 21 October 1997 / Revised: 23 February 1998 / Accepted: 26 February 1998