An electrochemical immunosensor was developed for the ultrasensitive measurement of α-fetoprotein based on electrochemical stripping analysis of silver nanoparticles catalytically deposited by nanogold labels. The immunosensor was prepared by covalently immobilizing capture antibodies with glutaraldehyde ( GA) on chitosan-multi wall carbon nanotubes modified glassy carbon electrodes. Through a sandwich-type immunoreaction, antibody-functionalized AuNPs were captured onto the immunosensor surface, and further induced a subsequent silver deposition. The deposited AgNPs were then measured directly by anodic stripping analysis in KC1 solution. Under the optimal conditions, the calibration curve was linear over a-fetoprotein concentration in the range of 0. 02-200 μg/L, the linear regression equation is ΔI = -0. 13 -0. 11c(μg/L) (r =0. 992 8). The detection limit is 8 ng/ L. The electrochemical immunosensor was applied in the determination of a-fetoprotein in three serum samples. The relative standard deviation is no more than 6. 1% . The determination result is identical with the result of electrogenerated chemiluminescence method. The sensor showed acceptable reproducibility, stability and accuracy, indicating a promising potential in clinical diagnose.%制备了基于金标记物诱导银沉积电化学溶出分析的超灵敏甲胎蛋白传感器.通过壳聚糖将多壁碳纳米管修饰在玻碳电极上,利用戊二醛共价固定捕获抗体制得传感器.通过夹心免疫反应,抗体功能化的纳米金被捕获到传感器表面并进一步诱导银沉积.沉积的纳米银可在KCl溶液中直接通过阳极溶出法进行分析,从而实现对α-甲胎蛋白的检测.利用甲胎蛋白作为模型分析物,在0.02 ～ 200 μg/L范围内,电流强度随着甲胎蛋白的质量浓度呈线性降低(r=0.992 8),检出限(S/N=3)为8 ng/L.将该传感器用于3个血样中甲胎蛋白的测定,所得结果与电致化学发光法测定结果一致.该免疫传感器显示了良好的稳定性、重复性和准确度,在临床诊断中具有较好的应用前景.
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