Detection of Cardiac Biomarkers Using Micellar Electrokinetic Chromatography and a Cleavable Tag Immunoassay
作者:Meghan M. Caulum、Brian M. Murphy、Lauren M. Ramsay、Charles S. Henry
DOI:10.1021/ac070452v
日期:2007.7.1
Biomarkers provide clinicians with an important tool for disease assessment. Many different biomarkers have been discovered, but few of them suffice as stand-alone indicators for disease presence or prognosis. Because no single biomarker can be relied upon for accurate disease detection there has been a substantial push for new multianalyte screening methods. Furthermore, there is a need to push assays toward a point-of-care technology to reduce the time between clinical analysis and medical intervention and minimize artifacts created during sample storage. There currently are, however, few inexpensive multianalyte methods for disease detection that can function in a point-of-care setting. A new approach which bridges the gap between traditional immunoassays and high-density microarrays by utilizing microfluidics, immunoassays, and micellar electrokinetic chromatography (MEKC) is discussed here. This chemistry, the cleavable tag immunoassay (CTI), is a low- to medium-density heterogeneous immunoassay designed to detect 1−20 analytes simultaneously. Although similar to traditional sandwich immunoassays, this approach is unique because the signal is not imaged on the surface; instead, a fluorescent tag is chemically cleaved from the antibody and analyzed by microchip MEKC. In this report, the CTI chemistry is used for the detection of four cardiac biomarkers elevated in acute myocardial infarction. Limit of detection (LOD) and dynamic range are reported for all biomarkers with LODs on the order of low nanograms per milliliter to low picograms per milliliter. Most importantly, the dynamic range for each of the biomarkers spans the boundary between normal and elevated levels. Finally, elevated marker levels were measured in spiked human serum samples.
生物标志物为临床医生提供了一种重要的疾病评估工具。已经发现了许多不同的生物标志物,但很少有能够单独作为疾病存在或预后的指示器。由于没有单一生物标志物可以依赖于准确的疾病检测,因此对于新的多分析物筛查方法有相当大的推动。此外,需要推动检测技术向即时护理技术发展,以减少临床分析和医疗干预之间的时间,并最小化样品储存过程中产生的伪影。然而,目前很少有能够在即时护理环境下功能且廉价的多分析物疾病检测方法。这里讨论了一种利用微流控、免疫测定和胶束电动色谱(MEKC)桥接传统免疫测定和高密度微阵列的新方法。这种化学方法,即可切除标签免疫测定(CTI),是一种设计用于同时检测1至20种分析物的低至中密度异质免疫测定。尽管类似于传统的夹心免疫测定,但这种方法独特之处在于信号不是在表面上成像;相反,荧光标签从抗体中化学切除并通过微芯片MEKC分析。在本报告中,CTI化学方法用于检测在急性心肌梗死中升高的四种心脏生物标志物。报告了所有生物标志物的检测限(LOD)和动态范围,LOD在低纳克每毫升至低皮克每毫升的范围内。最重要的是,每种生物标志物的动态范围跨越了正常和升高水平之间的界限。最后,在添加了标记的人血清样品中测量了升高标志物的水平。