Liu Guodong, Lin Ying-Ying, Wang Jun, Wu Hong, Wai Chien M, Lin Yuehe
Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
Anal Chem. 2007 Oct 15;79(20):7644-53. doi: 10.1021/ac070691i. Epub 2007 Sep 19.
We describe a disposable electrochemical immunosensor diagnosis device that integrates the immunochromatographic strip technique with an electrochemical immunoassay and exploits quantum dot (QD, CdS@ZnS) as labels for amplifying signal output. The device takes advantage of the speed and low cost of the conventional immunochromatographic strip test and the high sensitivity of the nanoparticle-based electrochemical immunoassay. A sandwich immunoreaction was performed on the immunochromatographic strip, and the captured QD labels in the test zone were determined by highly sensitive stripping voltammetric measurement of the dissolved metallic component (cadmium) with a disposable screen-printed electrode, which is embedded underneath the membrane on the test zone. The new device coupled with a portable electrochemical analyzer shows great promise for in-field and point-of-care quantitative testing of disease-related protein biomarkers. The parameters (e.g., voltammetric measurement of QD labels, antibody immobilization, the loading amount of QD-antibody, and the immunoreaction time) that govern the sensitivity and reproducibility of the device were optimized with IgG model analyte. The voltammetric response of the optimized device is highly linear over the range of 0.1-10 ng mL(-1) IgG, and the limit of detection is estimated to be 30 pg mL(-1) in association with a 7-min immunoreaction time. The detection limit was improved to 10 pg mL(-1) using a 20-min immunoreaction time. The device has been successfully applied for the detection of prostate-specific antigen (PSA) in human serum sample with a detection limit of 20 pg mL(-1). The results were validated by using the commercial PSA enzyme-linked immunosorbent assay kit and showed high consistency. The new disposable electrochemical diagnosis device thus provides a rapid, clinically accurate, and quantitative tool for protein biomarker detection.
我们描述了一种一次性电化学免疫传感器诊断设备，该设备将免疫层析试纸技术与电化学免疫分析相结合，并利用量子点（QD，CdS@ZnS）作为标签来放大信号输出。该设备利用了传统免疫层析试纸测试的速度和低成本以及基于纳米颗粒的电化学免疫分析的高灵敏度。在免疫层析试纸上进行夹心免疫反应，通过使用嵌入在测试区膜下方的一次性丝网印刷电极对溶解的金属成分（镉）进行高灵敏度溶出伏安测量，来测定测试区捕获的量子点标签。这种新型设备与便携式电化学分析仪相结合，在现场和即时护理疾病相关蛋白质生物标志物的定量检测方面显示出巨大潜力。使用IgG模型分析物对影响该设备灵敏度和重现性的参数（例如量子点标签的伏安测量、抗体固定、量子点 - 抗体的负载量和免疫反应时间）进行了优化。优化后的设备在0.1 - 10 ng mL(-1) IgG范围内伏安响应呈高度线性，在免疫反应时间为7分钟时，检测限估计为30 pg mL(-1)。使用20分钟的免疫反应时间时，检测限提高到了10 pg mL(-1)。该设备已成功应用于人血清样本中前列腺特异性抗原（PSA）的检测，检测限为20 pg mL(-1)。结果通过使用商用PSA酶联免疫吸附测定试剂盒进行了验证，显示出高度一致性。因此，这种新型一次性电化学诊断设备为蛋白质生物标志物检测提供了一种快速、临床准确的定量工具。
