A secondary antibody format chemiluminescence immunoassay for the determination of estradiol in human serum

A competitive immunoassay for estradiol (E2) based on secondary antibody format was established. The donkey anti-rabbit IgG was used as the secondary antibody to coat micro-plates, and the horseradish peroxidase (HRP)-luminol-H₂O₂ chemiluminescent system with high sensitivity was chosen as the detection system. The addition of sodium trichloroacetate (CCl₃COONa) in the enzyme buffer as a replaceable packing material can realize directly analysis of E2 in human serum without extraction, which improved reproducibility and resolution of the assay. Additionally, the method showed specific recognition of estrogen, without cross-reaction for the major steroids (estrone (E1), estriol (E3), dihydrotestosterone (DHT), androstenedione, testosterone (T)) commonly found in human serum. The chemiluminescence immunoassay with secondary antibody can be applied to detect E2 with good precision at concentrations as low as 1.48 pg mL⁻¹. The proposed method has been successfully applied to the determination of E2 in 97 human sera and showed a good correlation compared with the commercially radioimmunoassay (RIA) kit with a correlative coefficient of 0.9881. This method has exhibited great potential in the fabrication of diagnostic kit and can be used in the clinical analysis of E2 in human serum.     

Development of a rapid and sensitivity magnetic chemiluminescence immunoassay for DNA methyltransferase 1 in human serum

DNA methyltransferase 1(DNMT1) is a useful biomarker for lung cancer in early clinical diagnosis. A rapid magnetic chemiluminescence immunoassay(MCLIA) for DNMT1 in human serum has been developed.Horseradish peroxidase(HRP)-second-Ab was used to labeled polyclonal antibodies of anti-DNMT1. DNMT1 in sample integrates with specific immunomagnetic beads and can constitute a supersandwiched immunoreaction. In magnetic field, nonspecific materials can be separated. After luminescent substrate luminol-H_2O_2-BIP was added, the relative light unit(RLU) of HRP was detected and was discovered to be directly proportional to the content of DNMT1 in sample. The correlative variables involved in the MCLIA value were optimized and the methodological evaluation was carried out. After optimization, in the range of0.5–128 ng/mL, the linear regression equation was y = 0.5014 x + 1.769(x was logCDNMT1, y was relative luminescence units(RLU)/RLU0), and the limit of detection was 0.01 ng/mL. The RSD of intra-and interassays were 15.8%–16.9% and 14.3%–18.1%, respectively. The recovery was from 70.0% to 106.2%.Furthermore, paralleled with purchasable enzyme-linked immunosorbent assay(ELISA) kits, MCLEIA had lower detection limit, wider linear range and shorter detection time. Therefore, the MCLEIA established in this study could be used for the sensitive detection of DNMT1 in serum sample.     

Chemiluminescence enzyme immunoassay using magnetic nanoparticles for detection of neuron specific enolase in human serum

To detect a biomarker for small cell lung carcinoma, neuron specific enolase (NSE), a sensitive and specific chemiluminescence enzyme immunoassay was developed. Fluorescein isothiocyanate (FITC) labeled NSE capture antibody connected with NSE and alkaline phosphatase (ALP) labeled NSE detection antibody in a sandwich-type detection manner. This immune complex was further reacted with anti-FITC coated magnetic beads. In a magnetic field, the complex was enriched, and the sensitivity was thus enhanced. The limit of detection (LOD) of this method was <0.2 ng mL⁻¹. The proposed immunoassay was highly selective, and not interfered by hook effect. The recovery was >83.0% and the coefficient of variation was <10.0%. Human sera from 120 patients were tested with the presented and traditional chemiluminescence enzyme immunoassay. An excellent linear relationship was obtained between two techniques. Overall, this immunoassay offers a promising alternative for NSE detection than traditional clinical examinations.     

Direct chemiluminescence determination of cysteine in human serum using quinine-Ce(IV) system

A simple, sensitive and selective chemiluminescence (CL) method was developed for the determination of cysteine. This method is based on that the weak CL of cysteine oxidized with cerium (IV) can be greatly enhanced by quinine. The calibration curve was linear over the range 3.5×10⁻⁹-3.5×10⁻⁶ M with a detection limit of 2.5×10⁻⁹ M (S/N=3). The RSD was found to be 8.4% by 10 replicate determinations of 2.9×10⁻⁸ M cysteine. Due to high sensitivity, the proposed method can be used directly to determine the total concentration of cysteine in human serum through simply diluting the sample for a thousand fold. The obtained result was in agreement with that given by amino acid autoanalyzer. The present method does not require any separation, showing a simpler analytical characteristic. The mechanism of the CL reaction was also discussed.     

癌胚抗原毛细管电泳-化学发光均相免疫分析

设计了一种测定人血清中癌胚抗原的毛细管电泳-化学发光检测均相免疫分析新方法。采用四苯硼酸钠增强luminol-H2O2-HRP体系化学发光的原理,化学发光检测经毛细管电泳分离的,用辣根过氧化物酶(HRP)标记的癌胚抗体及免疫复合物。测定癌胚抗原的线性范围2.0~80.0μg/L(R=0.9921),检出限为0.1μg/L(绝对检出限为0.75 fg)。     

癌胚抗原毛细管电泳-化学发光均相免疫分析

建立了一种测定人血清中癌胚抗原的毛细管电泳-化学发光检测的均相免疫分析新方法.采用四苯硼钠增强luminol-H2 O2-HRP体系化学发光的原理,化学发光检测经毛细管电泳分离的,用辣根过氧化物酶(HRP)标记的癌胚抗体及免疫复合物.测定癌胚抗原的线性范围2.0～80.0 μg/L(R=0.9921),检出限为0.1 μg/L(绝对检出限为0.75 fg).     

Sub-picogram determination of Vitamin B12 in pharmaceuticals and human serum using flow injection with chemiluminescence detection

A sensitive chemiluminescence (CL) method, based on the enhancive effect of cobalt(II) on the CL reaction between luminol and dissolved oxygen in a flow injection (FI) system, was proposed for determination of Vitamin B₁₂. The increment of the CL intensity was proportional to the concentration of Vitamin B₁₂, giving a calibration graph linear over the concentration from 2.0×10⁻¹⁰ to 1.2×10⁻⁶ g l⁻¹ (r²=0.9992) with the detection limit of 5.0×10⁻¹¹ g l⁻¹ (3σ). At a flow rate of 2.0 ml min⁻¹, a complete determination of Vitamin B₁₂, including sampling and washing, could be accomplished in 0.5 min with the relative standard deviations (R.S.D.) of less than 5.0%. The proposed method was applied successfully to the determination of Vitamin B₁₂ in pharmaceuticals, human serum, egg yolk and fish tissue.     

Determination of total bilirubin in human serum by chemiluminescence from the reaction of bilirubin and peroxynitrite

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 ( ) during the decomposition of ONOO⁻. Bilirubin and its conjugate were found to enhance the CL emission of 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 8 ng ml⁻¹, respectively. The relative standard deviations (R.S.D.) for the consecutive CL detection of a series of bilirubin (30 μg l⁻¹) and bilirubin ditaurite (25 μg l⁻¹) were 3.2 and 2.9% (n=11), respectively.     

Ligand fishing from Dioscorea nipponica extract using human serum albumin functionalized magnetic nanoparticles

Dioscorea nipponica and the preparations made from it have been used for long to prevent and treat coronary heart disease in traditional Chinese medicine. A group of steroidal saponins present in the plant are believed to be the active ingredients. It has been a challenge to study the individual saponins separately due to the similarities in their chemical and physical properties. In this work, human serum albumin (HSA) functionalized magnetic nanoparticles (MNPs) were used to isolate and identify saponin ligands that bind to HSA from D. nipponica extract. Electrospray ionization mass spectrometry (ESI-MS) was used for compound identification and semi-quantification. Three saponins, i.e. dioscin, gracillin, and pseudo-protodioscin showed affinity to HSA-MNPs and thus isolated effectively from the extract. The other two saponins detected in the extract (i.e. protodioscin and 26-O-β-d-glucopyranosyl-3β,20α,26-triol-25(R)-Δ^5,22-dienofurostan-3-O-α-l-rhamnopyranosyl (1→2)-[α-l-rhamnopyranosyl (1 → 4)]-β-d-glucopyranoside) exhibited no affinity at all. Among the three saponins fished out, dioscin bound to HSA much stronger than gracillin and pseudo-protodioscin did. The results indicated that affinity interaction between HSA immobilized on MNPs and small molecule compounds were highly dependent on chemical structures and, potentially, medicinal usefulness. The present work demonstrates a facile and effective way to isolate and identify ligands of receptors from medicinal plants.     

Determination of proline in wine using flow injection analysis with tris(2,2'-bipyridyl)ruthenium(II) chemiluminescence detection

Flow injection methodology is described for the determination of proline in red and white wines using tris(2,2′-bipyridyl)ruthenium(II) chemiluminescence detection. Selective conditions were achieved for proline at pH 10, while other amino acids and wine components did not interfere. The precision of the method was less than 1.00% (R.S.D.) for five replicates of a standard (4 × 10⁻⁶ M) and the detection limit was 1 × 10⁻⁸ M. The level of proline in white and sparkling wines using the developed methodology was equivalent to those achieved using HPLC-FMOC amino acid analysis. SPE removal of phenolic material was required for red wines to minimize Ru(bipy)₃³⁺ consumption and its associated effect on accuracy.     

Modulated potential electrogenerated chemiluminescence of luminol and Ru(bpy) 3 2+

Chemiluminescence emission intensity is modulated by modulating the potential of a working electrode which is used to generate a key species in the electrogenerated Chemiluminescence (ECL) reaction. The emission is monitored synchronously using a lock-in amplifier. The reactions used in the characterization are luminol with hydrogen peroxide and tris(2,2-bipyridyl)ruthenium (II) (or Ru(bpy) ₃ ²⁺ ) with oxalate. Modulation widths of ± 50 mV yield maximum signals for luminol when centered at 0.45 V (vs Ag/AgCl) and for Ru(bpy) ₃ ²⁺ when centered at 1.05 V. The resulting signal decreases with increasing modulation frequency and shows that luminol/H₂O₂ is a faster ECL system than Ru(bpy) ₃ ²⁺ /oxalate. Working curves for luminol and for oxalate have essentially the same linear range and slope with the modulated potential approach as with a DC electrode potential. This approach provides capability for differentiating the analytical signal from constant background emission or stray light.     

Oxidation of ultra high molecular weight polyethylene (UHMWPE) part 3: Decomposition of hydroperoxides with SO2 and its effect on the chemiluminescence signal

Samples of slightly oxidised UHMWPE were treated with SO₂ to decompose hydroperoxides prior to chemiluminescence measurements. It was found that the effect was quite substantial, but it was not just due to the elimination of hydroperoxides; a stabilising effect was also manifested. This effect increased with an increasing concentration of hydroperoxides in the samples. The stabilising effect could not be seen in fresh samples or when the hydroperoxides were decomposed by heating the sample in nitrogen. In addition, a stabilising effect was also observed for samples in which the hydroperoxides were reduced by DMS. It was concluded that the stabilisation was due to the formation of H₂SO₄ in the case of SO₂ and DMSO in the case of DMS. Both these substances can act as stabilisers against oxidative degradation of polymers and were evenly distributed in the sample films after the reaction with the hydroperoxides.     

Online immunoaffinity assay-CE using magnetic nanobeads for the determination of anti-Helicobacter pylori IgG in human serum

About two-thirds of the world's population is infected with Helicobacter pylori (H. pylori). This Gram-negative bacterium is the most important etiological agent of chronic active type B gastritis and peptic ulcer diseases. Conventional methods such as gastric biopsy, ELISA and culture, require a long time for the determination of H. pylori infections. Moreover, the antibodies in human serum sample are capable to react immunologically with the purified H. pylori antigens immobilized on different kinds of support like magnetic nanobeads. In this study, we have developed an online immunoaffinity assay-CE to determine the concentration of anti-H. pylori IgG using magnetic nanobeads as a support of the immunological affinity ligands and an LIF as a detector. The separation was performed in 0.1 M glycine-HCl, pH 2, as the background electrolyte. The linear calibration curve to predict the concentration of H. pylori-specific immunoglobulin G antibodies in serum was produced within the range of 0.12-100 U/mL. The linear regression equation was i = 492.86+96.03 × C(anti-H. pylori), with the linear regression coefficient r(2) = 0.999. The LOD calculated by fluorescence detection procedure was of 0.06 U/mL. The whole assay was done in no more than 35 min and it was entirely automatized. The development of immunoaffinity assay-CE in this study demonstrates that there is a large possibility to introduce nanotechnology in several fields with significant advantages over the classic methodologies. Our proposition comprises the diagnosis and screening field.     

Determination of indole-3-acetic acid and indole-3-butyric acid in mung bean sprouts using high performance liquid chromatography with immobilized Ru(bpy)3-KMnO4 chemiluminescence detection

A novel method for determination of indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) in an extract from mung bean sprouts using high performance liquid chromatography (HPLC) with chemiluminescence (CL) detection is described. The method is based on the CL reaction of auxin (indole-3-acetic acid and indole-3-butyric acid) with acidic potassium permanganate (KMnO₄) and tris(2,2′-bipyridyl)ruthenium(II), which was immobilized on the cationic ion-exchange resin. The chromatographic separation was performed on a Nucleosil RP-C18 column (i.d.: 250 mm × 4.6 mm, particle size: 5 μm, pore size: 100) with an isocratic mobile phase consisting of methanol-water-acetic acid (45:55:1, v/v/v). At a flow rate of 1.0 mL min⁻¹, the total run time was 20 min. Under the optimal conditions, the linear ranges were 5.0 × 10⁻⁸ to 5.0 × 10⁻⁶ g mL⁻¹ and 5.0 × 10⁻⁷ to 1.0 × 10⁻⁵ g mL⁻¹ for IAA and IBA, respectively. The detection limits were 2.0 × 10⁻⁸ g mL⁻¹ and 2.0 × 10⁻⁷ g mL⁻¹ for IAA and IBA, respectively. The relative standard deviation (RSD) of intra-day were 3.1% and 2.3% (n = 11) for 2 × 10⁻⁶ g mL⁻¹ IAA and 2 × 10⁻⁶ g mL⁻¹ IBA; The relative standard deviations of inter-day precision were 6.9% and 4.9% for 2 × 10⁻⁶ g mL⁻¹ IAA and 2 × 10⁻⁶ g mL⁻¹ IBA. The proposed method had been successfully applied to the determination of auxin in mung bean sprouts.     

Quantitative analysis of human serum leptin using a nanoarray protein chip based on single-molecule sandwich immunoassay

We report a method for the quantitative analysis of human serum leptin, which is a protein hormone associated with obesity, using a nanoarray protein chip based on a single-molecule sandwich immunoassay. The nanoarray patterning of a biotin-probe with a spot diameter of 150 nm on a self-assembled monolayer functionalized by MPTMS on a glass substrate was successfully accomplished using atomic force microscopy (AFM)-based dip-pen nanolithography (DPN). Unlabeled leptin protein molecules in human serum were detected based on the sandwich fluorescence immunoassay by total internal reflection fluorescence microscopy (TIRFM). The linear regression equation for leptin in the range of 100 zM-400 aM was determined to be y = 456.35x + 80,382 (R = 0.9901). The accuracy and sensitivity of the chip assay were clinically validated by comparing the leptin level in adult serum obtained by this method with those measured using the enzyme-linked immunosorbent assay (ELISA) performed with the same leptin standards and serum samples. In contrast to conventional ELISA techniques, the proposed chip methodology exhibited the advantages of ultra-sensitivity, a smaller sample volume and faster analysis time.     

傅里叶变换近红外光谱法快速检测人血清生化成分

应用傅里叶变换近红外光谱透射技术结合偏最小二乘法(PLS)建立了人血清中7种生化成分的定标模型,利用内部交叉验证和自动优化功能对定标模型进行了优化,确定了最优建模参数。模型对人血清中总胆固醇、甘油三酯、总蛋白、白蛋白、载脂蛋白B、低密度脂蛋白胆固醇、葡萄糖定标样品集的预测值与化学值的相关系数r分别为0.9011、0.9593、0.9249、0.761、0.8831、0.5191、0 9148,预测校正标准误差RMSECV分别为15mg/dL,21.6mg/dL,2 66g/L,3 96g/L,0.091g/L,16.2mg/dL,0.49mmol/L。     

毛细管电泳-化学发光法测定人血清中的异烟肼

基于碱性介质中异烟肼对laminol-K3Fe(CN)6化学发光体系的增敏作用,设计了一个经毛细管电泳(CE)分离,在线化学发光检测异烟肼的新方法.研究并优化了毛细管电泳分离及化学发光检测的条件.在优化的实验条件下,该方法测定异烟肼的线性范围为4.0×10-7～1.0×10-5g/mL(R2=0.9984),检出限(3σ)为1×10-8g/mL,对6.0×10-6g/mL的异烟肼进行6次平行测定,其相对标准偏差为4.0%.方法已用于血清中异烟肼的测定.     

Development of an Ultra-sensitive Chemiluminescence Enzyme Immunoassay for the Determination of Diethylstilbestrol in Seafood

An ultra-sensitive indirect competitive chemiluminescence enzyme immunoassay was developed for screening diethylstilbestrol in fish and shrimp samples. The concentration of diethylstilbestrol that caused 50% inhibition of the binding enzyme marker (IC₅₀) was 0.32 ng/mL and the limit of detection was 0.0068 ng/mL; the linear range was from 0.028 ng/mL to 3.60 ng/mL. The assay showed cross-reactivity of 7.1% and 2.8% with dienestrol and hexoestrol, respectively, but negligible cross-reactivity with estradiol, estrone, ethinyloestradiol, and progestin. The recovery from spiked fish and shrimp samples varied from 68.5% to 92.5%, and the mean coefficients of variation within groups and between groups were 6.2% and 8.0%, respectively. Our results indicated that the assay is a simple, sensitive, specific, and accurate method for screening fish and shrimp samples for diethylstilbestrol.     

流动注射比浊法测定人体血清总蛋白

基于磺基水杨酸 硫酸钠混合试剂与蛋白质发生浊度反应,设计了具有一个汇合点的FIA单道流路,运用正交实验优化了影响比浊反应的主要因素,并探讨了流动注射分析条件,从而提出了流动注射比浊法测定人血清中总蛋白的新方法。本法实验结果与双缩脲法一致,每小时进样60次,线性范围为0.14～1.40mg mL。     

TiO_2溶胶二级散射光谱法测定人血清白蛋白

制备了TiO2溶胶,并通过透射电子显微镜等对其结构进行了表征。研究了TiO2溶胶与人血清白蛋白(HSA)的相互作用。基于HSA对TiO2溶胶二级散射峰的增强作用,建立了二级散射光谱法测定痕量白蛋白的新方法。方法的线性范围是0.005~1.5 mg/L,检出限为3.5μg/L。方法用于人血中HSA的测定,回收率为98%~100.2%。