纳米金标记-膜过滤分光光度法检测免疫球蛋白G

Immunonanogold-labeled spectrophotometric determination of trace IgG based on membrane filtration

采用10 nm的纳米金标记羊抗人免疫球蛋白G获得免疫球蛋白G（IgG）的探针（AuIgG）。在pH 6.8的NaH2PO4-Na2HPO4磷酸盐缓冲溶液及聚乙二醇6000、KCl溶液存在下,IgG与AuIgG探针发生免疫反应,用0.15μm滤膜过滤反应生成的免疫复合物溶液,滤液在524 nm处有一最大吸收峰。其降低值ΔA524 nm随着IgG浓度的增加线性增加,据此建立了一种测定IgG的分光光度法。在最佳实验条件下,免疫球蛋白G浓度在0.025～0.375μg/mL范围内与ΔA呈良好的线性关系,其线性回归方程为ΔA=0.783ρ＋0.0232,相关系数为0.9927,检出限（3σ）为0.0082μg/mL。该法用于分析人血清中免疫球蛋白G,结果与免疫透射比浊法结果一致,相对标准偏差在2.0%～5.6%之间。

Nanogold particles of 10 nm were used to label goat anti-human IgG（GIgG） to obtain nanogold-labeled IgG（AuIgG）.In the pH 6.8 NaH2PO4-Na2HPO4 buffer solution and in the presence of polyethylene glycol（PEG） 6000 and KCl,AuGIgG combined with IgG and aggregated to form immunocomplex AuIgG-IgG particles by Val der Waals force,hydrophobic force,coulomb attracting force and hydrogen bond binding force,and nanogold particles form larger nanogold clusters that can be removed by membrane filtration.With addition of IgG, the decreased AA value of solution increased linearly. Thus, a new spectrophotometric method was proposed. Under the chosen conditions, the de- creased ΔA value at 524 nm was proportional to the concentration of IgG in the range of 0.025 - 0.375μg/mL, the re- gression equation was ΔA524, m = 0.783ρ ＋ 0.0232, and correlation coefficient was 0.9927, with a detection limit of 0. 0082/～g/mL. This assay was applied to the analysis of IgG in human sere, which was also determined by the immunoturbidimetric method, and both results were consistent. The RSDs were 2.0% ～ 5.6%. The method has high sensitivity, high selectivity and rapidity.