磁性纳米金共价固定癌胚抗原单克隆抗体的电流型免疫传感器

Amperometric Immunosensor Based on Covalent Immobilization of Monoclonal Carcinoembryonic Antibody(CEA) on Fe_3O_4/Au Nanocomposites

合成了Fe3O4/Au磁性复合纳米粒子,在粒子表面通过自组装硫脲分子使表面氨基化,再用戊二醛共价交联固定癌胚抗原抗体（anti-CEA）.在外加磁场的作用下,将anti-CEA复合磁性粒子吸附在固体石蜡碳糊电极表面,制成了新型电流型免疫传感器.免疫电极在含有癌胚抗原CEA和辣根过氧化物酶标记的癌胚抗原（HRP-CEA）的混合溶液中温育,CEA和HRP-CEA与固定在电极表面的anti-CEA发生竞争反应,导致HRP对H2O2的催化降解作用的改变,从而可间接测定CEA.由于标记的HRP可催化降解H2O2,导致媒介体间苯二酚浓度改变,使测定的灵敏度大大提高.响应电流与CEA质量浓度的对数在2～160 ng/mL的范围内呈线性关系,检出限为0.57 ng/mL（3σ法）.该免疫传感器具有制作简单、价廉及表面易于更新等特点.

Fe3O4/Au magnetic nanocomposites were synthesized, then the surface of the magnetic nanocomposites was amino-functionalized with thiourea to covalent immobilization of monoclona carcinoembryonic anti-body（anti-CEA） using glutaraldehyde. The resulting magnetic bio-nanocomposites were attached onto the surface of solid paraffin carbon paste electrode with the help of a permanent magnet to construct a new amperometic immunosensor. The immunosensor was incubated with mixed solution of carcinoembryonic antigen （CEA） and horseradish peroxidase labeled carcinoembryonic antigen（HRP-CEA） for 30 min to perform the competitive immune reaction between CEA （or HRP-CEA） and anti-CEA immobilizated on the surface. The concentrations of CEA were determined indirectly by competitive immunoassay method via the changes of the H2O2 concentrations resulted from the catalytic degradation by HRP. The sensitivity for CEA determination was greatly improved due to the amplification effect of labeled HRP on the catalytic degradation of H2O2, which led to the change of the concentration of p-hydroquinone. There is a linear relation between response current and logarithm of concentrations of CEA in the concentration range of 2-160 ng/mL, with a detect limit of 0. 57 ng/mL（ on a 3σ basis）. The simple manipulations of construction, low cost, high sensitivity, sharp specificity and easy regeneration of the sensing platform were main advantages of proposed immunosensor.