Determination of Hydrocortisone in Cosmetics by CdSe/CdS Quantum Dots-Based Fluoroimmunoassay Using Magnetic Fe3O4/Au Nanoparticles as Solid Carriers

This work demonstrated the feasibility of detecting hydrocortisone in cosmetics using a novel CdSe/CdS quantum dots‐based competitive fluoroimmunoassay with magnetic core/shell Fe₃O₄/Au nanoparticles (MCFN) as solid carriers. Hydrocortisone antigen was labeled with the synthesized core/shell CdSe/CdS quantum dots (QDs) to form the antigen‐QDs conjugate. Meanwhile, hydrocortisone antibody was incubated with MCFN and the immobilized antibody was obtained. The immobilized antibody was then mixed sequentially with hydrocortisone and a slightly excess amount of the QDs‐labeled hydrocortisone antigen, allowing their competition for binding with the antibody immobilized on MCFN. The bound hydrocortisone and the antigen‐QDs conjugates on MCFN were removed subsequently after the mixture was applied to a magnetic force. The analyte concentration was obtained by measuring the fluorescence intensity of the unbound hydrocortisone antigen‐QDs conjugates. The proposed method was characterized by simplicity, rapidity, and high sensitivity with a wide linear working range of 0.5 to 15000 pg·mL^?1 and a low detection limit of 0.5 pg·mL^?1. The proposed method was successfully applied to the determination of hydrocortisone in cosmetics with satisfactory results.     

铽标记人血清白蛋白的荧光光谱及应用

本文研究了由对-氨基水杨酸衍生的铽资合物及其标记人血清白蛋白的荧光光谱;测量了它们的激发态寿命.首次提出铽资合物标记蛋白质中蛋白质对Tb3+离子发光无影响.建立了液相中竞争性的人血清白蛋白的荧光免疫分析法.     

Development of a Time-Resolved Fluoroimmunoassay for the Rapid Detection of Methyl-3-Quinoxaline-2-Carboxylic Acid in Porcine Tissues

A time-resolved fluoroimmunoassay for the specific determination of methyl-3-quinoxaline-2-carboxylic acid in animal tissues, a marker residue of olaquindox, was developed. The IC₅₀ of the assay was found to be 1.46 ± 0.19 ng/mL of methyl-3-quinoxaline-2-carboxylic acid in phosphate-buffered saline samples and the detection limit was 0.16 ± 0.03 ng/mL. For porcine liver and muscle samples spiked with 5, 10, and 15 ng/g, the recovery ranges were 95.7–112.3% and 98.5–116.2% and the coefficients of variation were 9.3–11.5% and 8.9–14.2%, respectively. The time-resolved fluoroimmunoassay results correlated well with high performance liquid chromatography results (correlation coefficients of 0.991 for liver and 0.988 for muscle). This study suggests that this method is simple, fast, and sensitive for the high-throughput determination of methyl-3-quinoxaline-2-carboxylic acid in animal tissues.     

Study on the New Fluorescence Immunoassays for the 2,4,6‐Trichlorophenol in the Environmental Water

Abstract

This study reported that the hapten of 2,4,6‐trichlorophenol (2,4,6‐TCP) was synthesized by using 2,4,6‐TCP reacted with chloroactic acid in alkaline solution. The hapten was conjugated to bovine serum albumin (BSA) with the modified active ester method to form artificial immune antigen. The anti‐TCP polyclonal antibodies were obtained by using the artificial immuneantigen (TCP‐BSA) to immunize the rabbits. Using the purified antiserum of highest specificity, an antibody‐coated fluoroimmunoassay was developed that shows an IC₅₀ of 4.8 µg/L with a limit of detection of 0.25 µg/L. The antibody showed negligible cross‐reactivity with other phenols, which makes their assays suitable for the selective detection of 2,4,6‐TCP. It shows a good accuracy and suitability to analyze, 2,4,6‐TCP in environmental water.     

A monoclonal antibody-based time-resolved fluoroimmunoassay for chloramphenicol in shrimp and chicken muscle

A time-resolved fluoroimmunoassay (TR-FIA) for determination of chloramphenicol (CAP) in shrimp and chicken muscle was developed. The method was based on a direct competitive immunoassay using europium-labeled anti-CAP monoclonal antibody (MAb) and CAP-ovalbumin as coated antigen. The limit of detection was 0.05 ng g⁻¹ and limit of quantification was 0.1 ng g⁻¹. Recoveries ranged from 101.2 to 112.5% for shrimp and 104.9 to 115.3% for chicken muscle at spiked levels of 0.1-5 ng g⁻¹, with intra-assay and inter-assay variations 8.7-14.6 and 9.6-17.8%, respectively. The results obtained by the TR-FIA and ELISA correlated well. The established TR-FIA was validated for the determination of incurred shrimp samples and confirmed by gas chromatography with microcell electron capture detector (GC-μECD).     

稀土有机螯合物发光研究进展

总结了稀土有机螯合物结构与发光性能的关系：配体最低三重态能级与稀土离子激发态能级的匹配是中心稀土离子能否发光的主要因素;螯合物结构的平面性和刚性是中心离子发光效率高低的重要因素;适宜的第二配体的加入一般导致螯合物分子刚性和稳定性增高,因而有利于能量的传递,致使中心离子发光效率增高,但也不能忽视第二配体加入所引起光能的吸收和能量传递过程的竞争;配体的耐热,耐辐射性是配合物能否作为材料的必要因素,自行设计,合成了5类25种新的有机配体及其相应的二元,三元稀土螯合物,研究了这些螯合物的配位性质,发光性能,发光与结构关系及发光机制。提出并发展了稀土离子发光和电子振动光谱作为配合物和生物分子结构探针的两种新的方法。将稀土－β－二酮的发光螯合物与树脂制成荧光塑料;利用铕和铽螯合物的发光和免疫反应,检测了体液中生物活性物质的含量,证实以稀土离子替代放射性同位素作为标记物,有希望替代放射免疫分析方法,成为常规的临床检验方法,利用Tb^3 荧光检测了植物中生长激素的含量。     

A phase separation fluoroimmunoassay of estradiol

A competitive indirect fluoroimmunoassay of free estradiol (E₂) was established based on the thermal sensitivity of hydrogel–‐poly‐N‐isopropylacrylamide. Free estradiol was covalently bound to bovine serum albumin (BSA) to form complete antigen (E₂‐BSA), which was in turn labeled by fluorescein isothiocyanate (FTTC) as the fluorescence probe. The anti‐ E₂ monoclonal antibody (McAb) was prepared by an in vivo method, and coupled with N‐isopropylacrylamide (NIPA) to make an immune copolymer, poly‐N‐isopropylacylamidemonoclonal antibody (pNIPA‐McAb), for the determination of free E₂. The immunoassay method was based on the competitive binding of free E₂ and fluoresceinated antigen (E₂‐BSA‐FTTC) with limited amount of pNIPA‐McAb. When the immunological reaction was over, precipitation and centrifugal procedures were carried out to separate pNIPA‐McAb‐E₂‐BSA‐FTTC from other constituents in solution. The precipitate pNIPA‐McAb‐E₂‐BSA‐FTTC was dissolved in solution and then the fluorescence intensity was measured. The calibration curve covered a range of 78–500 ng/mL for free E₂. The recoveries were 91.2–107.2%.     

Determination of Diethylstilbestrol by Time-resolve Fluoroimmunoassay

Abstract

A time-resolved fluoroimmunoassay (TRFIA) was developed for the determination of diethylstilbestrol (DES). The method was based on a competitive immunoassay using europium-labeled anti-DES antibody and DES-bovine serum albumin (DES-BSA) as coated antigen. The TRFIA exhibited a typical response for DES at concentrations of 0.001–100 ng · mL^?1, the linear correlation coefficient is 0.9933, and the detection limit (LOD) is 0.595 pg · mL^?1. Some serum and water samples have been analyzed by using this method with satisfactory results. Compared with the routine fluorescence immunoassay (FIA), this method was more sensitive. The TRFIA may offer a valuable alternative method for the DES detection and could be applied to routine analysis.     

Detection of 2,4-Dichlorophenoxyacetic Acid by Microtiter Particle Agglutination Inhibition Test and Polarisation Fluoroimmunoassay

Abstract

A simple microtiter particle agglutination inhibition (MPAI) assay for detection of 2,4-dichlorphenoxyacetic acid (2,4-D) has been developed on the basis of coloured polyacrolein latex particles sensitized with monoclonal antibodies to 2,4-D. MPAI test has been applied to the quantification of 2,4-D in water and extracts from grain and compared with the polarisation fluoroimmunoassay. The detection limit of 2,4-dichlorphenoxyacetic acid in MPAI was 0.6 μg/1 which was about two orders higher than that of polarisation fluoroimmunoassay. The cross-reactivity of various structurally related substances was less than 10.%. Good correlation of MPAI and polarisation fluoroimmunoassay was shown when testing 2,4-D in the extracts from grain. MPAI assay is rapid, robust, easy to perform, doesn't need any instrumentation and specially trained personnel.     

Quantum-dot-based homogeneous time-resolved fluoroimmunoassay of alpha-fetoprotein

Quantum dots (QDs) with novel photoproperties are not widely used in clinic diagnosis, and homogeneous time-resolved fluorescence assays possess many advantages over current methods for alpha-fetoprotein (AFP) detection. A novel QD-based homogeneous time-resolved fluorescence assay was developed and used for detection of AFP, a primary marker for many cancers and diseases. QD-doped carboxyl-modified polystyrene microparticles (QPs) were prepared by doping oil-soluble QDs possessing a 605 nm emission peak. The antibody conjugates (QPs-E014) were prepared from QPs and an anti-AFP monoclonal antibody, and luminescent terbium chelates (LTCs) were prepared and conjugated to a second anti-AFP monoclonal antibody (LTCs-E010). In a double-antibodies sandwich structure, QPs-E014 and LTCs-E010 were used for detection of AFP, serving as energy acceptor and donor, respectively, with an AFP bridge. The results demonstrated that the luminescence lifetime of these QPs was sufficiently long for use in a time-resolved fluoroassay, with the efficiency of time-resolved Förster resonance transfer (TR-FRET) at 67.3% and the spatial distance of the donor to acceptor calculated to be 66.1 Å. Signals from TR-FRET were found to be proportional to AFP concentrations. The resulting standard curve was log Y = 3.65786 + 0.43863·log X (R = 0.996) with Y the QPs fluorescence intensity and X the AFP concentration; the calculated sensitivity was 0.4 ng mL⁻¹. By assaying test samples against the standard curve, the coefficient of variations was <5%, indicating that QDs were suitable for this homogenous time-resolved fluoroimmunoassay. This work extended the potential applications of QDs in future homogeneous analytical bioassays. In the coming research, hepatitis B surface antigen, another primary marker for hepatocellular carcinoma, will be studied for practical detection using a QD-based homogenous multiplex fluoroimmunoassay.