毛细管电泳免疫分析法研究癌胚抗原与抗体相互作用

采用毛细管电泳免疫分析法研究癌胚抗原和抗体相互作用.探讨了缓冲体系、癌胚抗原和抗体的配比、进样时间,进样电压等因素对分离检测的影响.结果表明分离电压为14 kV,进样时间为10 s, 在pH值为5.92的Tris-乙酸缓冲体系（TAE）中, 癌胚抗原及其复合物得到较满意的分离.     

Relation of Microbes to Blood-Group Active Substances

Substances with blood-group ABH(0) specificity are not confined to human red blood cells. Rather, such substances are ubiquitous antigenic surface structures which Nature has preserved throughout the phylogenetic development from microbes to man. — It could be shown experimentally that so-called “pre-existing natural” antibodies can result from inapparent immunization by these widely distributed antigens. — The blood-group specific structures of bacteria are chemically closely related to the determinant structures of the human blood-group ABH(0) glycoproteins. The situation is more complicated for the blood-group active substances from higher plants; these give extraordinary immunochemical reactions and two of their blood-group specific monosaccharides precipitate antibodies. — Recently the nature of the M and N blood-group antigens of erythrocyte surfaces has been elucidated. They are the main antigens of the second of at least 14 human blood-group systems. These substances, which are glycoproteins, are also excellent myxovirus receptors and inhibitors. The NN antigen is the first reported physically homogeneous, chemically defined and highly blood-group active cell surface structure of human origin. As surface structures, blood-group active substances appear to be frequently endowed with receptor properties in addition to those for blood-group antibodies.     

Electroanalytical Determination of Carcinoembryonic Antigen at a Silica Nanoparticles/Titania Sol–Gel Composite Membrane‐Modified Gold Electrode

A highly hydrophilic and nontoxic colloidal silica nanoparticle/titania sol–gel composite membrane was prepared on a gold electrode via a chemical vapor deposition method. With carcinoembryonic antigen (CEA) as a model antigen and encapsulation of carcinoembryonic antibody (anti‐CEA) in the composite architecture, this membrane could be used for reagentless electrochemical immunoassay. The presence of silica nanoparticles provided a congenial microenvironment for adsorbed biomolecules. The formation of immunoconjugate by a simple one‐step immunoreaction between CEA in sample solution and the immobilized anti‐CEA introduced the change in the potential. The modified procedure was further characterized by electrochemical impedance spectroscopy and cyclic voltammetry. Compared to the commonly applied methods, i.e., the TiO₂ direct embedding procedure, this strategy could allow for antibodies immobilized with higher loading amount and better retained immunoactivity. The resulting immunosensor exhibited high sensitivity, good precision, acceptable stability, accuracy, reproducibility and wide linear range from 1.5 to 240 ng mL^?1 with a detection limit of 0.5 ng mL^?1 at 3σ. Analytical results of clinical samples show that the developed immunoassay is comparable with the enzyme‐linked immunosorbent assays (ELISAs) method, implying a promising alternative approach for detecting CEA in the clinical diagnosis. Furthermore, this composite membrane could be used efficiently for the entrapment of other biomarkers and clinical applications.     

Synthesis of a new biacridine and its use as the chemiluminescent probe for immunoassay of carcinoembryonic antigen

A new biacridine compound, 10,10′-dimethyl-3,3′-disulfo-9,9′-biacridine (DMDSBA) was synthesized, and its chemiluminescent characteristics were investigated in detail. DMDSBA was used to label anti-CEA antibody. The labeling ratio was estimated to be 1.15-1.32, and the average labeling ratio was 1.25. The results show that there are no obvious changes in the immunoreactivity of the labeled anti-CEA antibody and the quantum efficiency of DMDSBA after attaching to the anti-CEA antibody. In addition, the conditions of labeling reaction, sandwich immunoassay and chemiluminescent reaction have been studied. A new sandwich chemiluminescent immunoassay method was firstly established, and used to determine CEA in human serum, the calibration range is 1.0-100 ng ml⁻¹ and the minimal detectable concentration of CEA is 0.53 ng ml⁻¹, the relative standard deviation is 6.5% for 20 ng ml⁻¹ CEA. This method was well-matched with radio immunoassay.     

Carbon nanotube-based symbiotic coaxial nanocables with nanosilica and nanogold particles as labels for electrochemical immunoassay of carcinoembryonic antigen in biological fluids

A feasible and practicable amperometric immunoassay strategy for sensitive screening of carcinoembryonic antigen (CEA) in human serum was developed using carbon nanotube (CNT)-based symbiotic coaxial nanocables as labels. To construct such a nanocable, a thin layer of silica nanoparticles was coated on the CNT surface by sonication and sol-gel methods, and then colloidal gold nanoparticles were assembled on the amino-functionalized SiO₂/CNTs, which were used for the label of horseradish peroxidase-anti-CEA conjugates (HRP-anti-CEA-Au/SiO₂/CNT). In the presence of analyte CEA, the sandwich-type immunocomplex was formed on an anti-CEA/Au/thionine/Nafion-modified glassy carbon electrode by using HRP-anti-CEA-Au/SiO₂/CNTs as detection antibodies. To embody the advantages of the protocol, the analytical properties of variously modified electrodes were compared in detail on the basis of different nanolabels. Under optimal conditions, the cathodic peak currents of the electrochemical immunosensor were proportional to the logarithm of CEA concentration over the range from 0.01 to 12 ng mL⁻¹ in pH 5.5 HAc-NaAc containing 5 mM H₂O₂. At a signal-to-noise ratio of 3, the detection limit (LOD) is 5 pg mL⁻¹ CEA. Intra- and inter-assay coefficients of variation were below 9.5%. Meanwhile, the selectivity and stability of the immunosensor were acceptable. In addition, the technique was evaluated by spiking CEA standards in pH 7.4 PBS and with 35 clinical serum specimens, receiving excellent accordance with results from commercially available electrochemiluminescent enzyme-linked immunoassay.     

A Facile Electrochemical Immunosensor with Mesoporous Alumina for Detection of Carcinoembryonic Antigen

A label‐free electrochemical immunosensor for the sensitive determination of carcinoembryonic antigen (CEA) was fabricated by immobilizing anti‐CEA onto mesoporous alumina (meso‐Al₂O₃) dispersed in chitosan (0.5 %wt) by the cross‐linking method using glutaraldehyde. Due to its plenty of active sites, meso‐Al₂O₃ showed high catalysis towards hydroquinone. With the electrocatalytic ability of meso‐Al₂O₃ for the reduction of hydroquinone, the current signal of the antigen‐antibody reaction was amplified and the enhanced sensitivity was achieved. The current decreased linearly with CEA concentration in the range of 0.04 to 10 ng/mL (26 pg/mL, S/N=3). The immunosensor had good selectivity and wonderful stability. Furthermore it was applied to the analysis of CEA in serum sample with satisfactory results.